The study results of the content variation of organic carbon and its component in black soil during different tillage period show that both the content of TOC and its component decreasing and the soil Kos value increasing in ploughing layer and ploughing bottom layer are rapid at first 50 years cultivation. After 130 years tillage

the content of organic carbon and its component are relative stable on the whole. Total organism carbon content in ploughing layer of black soil lost 1.76%~24.81% after 200 years tillage. Among organic carbon component

the FA-C is affected relative little by tillage time

while Hu-C is affected seriously.