Base on the determination of soil age, spore-pollen in soil, composition of humus, soil micromorphology, X-ray diffraction, soil profile morphological character, soil physical and chemical properties, the genetic environment of dark loessial soil are discussed. The results show that dark loessial soil is a palesol. Many characteristics of dark loessial soil are the result of paleontology,climatic conditions. ¹⁴C soil age. The genesis of dark loessial soil includes three year ranges: 8100-8500 4600-7400, and 2000-3000 years B.P., which were cold in the climate. Spore-pollen appraisal. According to the appraisal of spore-pollen in Xian Luo-chuan, Ansai, Longxi and Xifeng,a conclusion can be drawn that the herb is predominant and the environment is cold and damp in the geneticperiod of dark loessial soil.