South China 205 of cassava was.taken.as the.research object，and a study was conducted to investigate the effect of fertilizer reduction on cassava root yield and quality under the Fenlong tillage. The results showed that:(1)With the fertilizer reduction，the cassava plant height，stem diameter，yield decreased under both traditional tillage and Fenlong tillage，However，the decline under Fenlong tillage was smaller，and 30% reduction of fertilizer treatment remained the similar yield with the treatment without fertilizer reduction under traditional tillage.(2)Fenlong tillage with reduction fertilizer management had no obvious effect on starch content and dry matter in fresh tuber，but significantly reduced hydrocyanic acid content. Therefore，about 30% reduction of fertilizer application can ensure the yield and quality of cassava under Fenlong tillage.