Abstract: The authors studied the effects of soil fertility maintainingand crop yield increase under straw mulch for five years in slope red earth insuccession. The results show as follows: the soil organic carbon and total N, Pcontent of "Straw +NP chemical fertilizer"("Straw+NP") treatment increased by 42.9%, 17.4% and 44.2% respectively than those of no chemical fertilizer(CK) treatment. It was approximately twice in the range of soil organic carbon and total N beingraised by "Straw+NP" treatment than by NPK chemical fertilizer(NPK) treatment.Compared with CK and NPK treatment, "Straw+NP" treatment can obviously improve the contents of red soil microbial biomass C, N, P, and dissolved organic C, N,Olsen-P, there are differences between fertilization treatment notability(P<0.05) or bally prominence(P<0.01). On the condition of nutrient dosage, "Straw+NP chemical fertilizer" treatment might obviously improve rape and sweet potatoyield. So, straw mulching is the most availability technique of soil fertilitymaintaining and crop yield increase in slope red soil.