Abstract: By a 24-year(1981-2004) long-term located fertilizer experiment,the effect of long-term combined application of organic and chemical fertilizers on fluvo-aquic soil fertility and crop yield was investigated in Hengshui,Hebei Province.The results showed that,both chemical and organic fertilization could significantly increase crop yield,but chemical fertilizer application was more effective.Combined application of organic straw and chemical fertilizer had a more pronounced yield response than single application of either.Applying chemical fertilizer also increased the soil organic matter content,but applying chemical fertilizer together with organic straw tended to accumulate more soil organic matter than single application of either.As to the compound quantity of soil organic matter,the chemical fertilizer proved to be better than that of straw,and combined application of both straw and chemical fertilizer was the best.The compound degree of soil organic matter decreased with the increasing single application rate of either straw or chemical fertilizer,but combined application of them could increase the compound degree of soil organic matter.The combining application of organic straw and chemical fertilizer could also improve soil physical properties: soil bulk density was lightened,field water holding capacity and soil saturated water content were increased,total soil porosity and soil capillary porosity were enhanced.Thus it was concluded that combining application of organic straw and chemical fertilizer could improve the fluvo-aquic soil fertility and increase crop yield.