Paleosols consist of soils formed under climate conditions different from the present day, consequently their physical properties are regarded as an indicator for past climate condition. Loess investigation have received considerable attention in twenty century. Loess- Paleosol sequences in Central Aia have attracted the attention of loess researchers. Major loess areas in Central Asia are located in the southern Tajikistan. The paleosols sequences in the loess sediments in the southern Tajikistan, which can reach thicknesses of 200 m- is a key area of environmental changes of Central Asia. Loess-paleosols sequences of the southern Tajikistan prove the cold and dry climate through loess deposition and the warm and humid climate during the formation of the paleosols. Tajikistan is a mountainous country which is surrounded by mountains to the north, east and south and the desert of central Asia to the west. The climate of Tajikistan is continental, subtropical and Semiarid, with drastic changes according to elevation. The Khonako II sedimentary section studied (latitude 38.35959 N, longitude 70.04552 E) is situated in southern Tajikistan. Present-day climate in southern Tajikistan is Mediterranean, with dry summers and seasonal precipitation spanning from early winter to spring. Recently micromorplological studies have not been published from this regin. The purpose of this study were to investigate the micromorphology of loess-paleosol sequences in the southern Tajikistan as well as compare the weathering and evolution of th loess and paleosol sequences of Tajikistan and Iran. The loess-paleosol section was described and undisturbed samples were collected from thin section analyses. Thin section study of paleosols is a uniqe method to study pedological changes in the past and paleoenvironmental reconstruction. The micromorphological index of soil development (MISECA), in which several micropedological feature (microstructure, b-fabric, the presence of clay coating, decalcified zons, Fe/Mn oxides and degree of alteration of mineral grains) explain accurate infoemation of the degree of soil development in the past in different horizons. Based on increasing grade of soil Evolution, the MISECA index ranges from 0 to 24. In the studied section, a modern soil (MS) including an ochric epipedon, and cambic and calcic subsurface horizons as well as twelve loess sequences(L) and sixteen pedocomplexes (PC), which are covered by thick (∼12000 cm) loess deposits and different types of interstadial and interglacial paleosols were identified. The micromorphological investigations indicate that the accumulation of clay illuviation, pedogenic calcium carbonate and depletion of the soil carbonate are the predominant processes in these soils. Various types of calcitic pedofeatures are recognized in the modern soil which imply that coating and hypocoating of secondary carbonates around channels result from later recalcification processes. The observed voids contain of planes, vughs, channel and chamber. Channels and chambers in the modern soil, some loess units and paleosols are attributed to biological activity. The dominant microstructure of modern soil is crumb due to organic matter. The microstructure differ from waekly-separated angular (subangular) blocky in the pedocomplexes with a lower degree of development to well-separates angular (subangular) blocky in the pedocomplexes with a higger degree of development. In PC10 clay coatings super imposed on carbonate coatings, and in turn covered by calcite, demonstrates recalcification. a crystallitic b-fabric were seen in soils with a higher amount of calcium carbonate. However, the part of argillic horizons was mostly dominated by spckled b-fabric, which demonstrates the process of translocation and subsequent accumulation of clay as a result of water percolation. Clay pedofeatures were recognize as clay coating along the channels. Disruption by swelling and shrinking in soil is the main factor responsible for the lower amount or lack of clay coatings in PC1. The appearance of numerous redoximorphic features in PC7 and PC8 in comparison to the other pedocomplexes indicate periodical saturation due to higher precipitation. Generally, large amounts of clay coatings, iron and manganese oxides pedofeatures, and biological activities features indicated the high development of paleosols compared to the loess layers. Investigation of micromorphological soil development index (MISECA Index) as a measure of soil development showed weak development for modern soil, in contrast of moderately to well-developed of paleosols due to having oriented clay coatings and iron and manganese oxides on soil grains or channels. Variations of MISECA index values of modern soil compared to paleosols demonstrates that paleosols were formed in the more humid conditions.