Abstract: By analysis of sporopollen in 0-1 m black soil profile PM25 in eastern Liaohe Plain, the fossils are divided into two sporopollen assemblages from bottom to top according to the sporopollen content change. The PM25-1 sporopollen assemblage is mainly Spiraea-Artemisia-Sanguisorba-Rosa-Echinate Asteraceae, with the climate changing from cold-dry to warm-wet; while the PM25-2 sporopollen assemblage is dominated by Pinus-Cyperaceae-Chenopodium, indicating the transition of climate from warm-wet to cold-dry. Combined with the ¹⁴C dating data, it is concluded that the black soil in eastern Liaohe Plain was mainly formed in Medieval Warm Period since 1335 a B.P.