【Objective】The aim of this experiment was to find out the best applying period for Astragalus sinicus and rapeseed manure in the soil to sustain the productivity of soil and enhance their application. 【Method】During 2009 and 2010, 5 manure application treatments were conducted at full-bloom stage and pod maturity stage of Astragalus sinicus and rapeseed， and blank control（no manure）， respectively. The fresh and dry matter contents were measured in all treatments. Further， the influence of different field-returning methods of Astragalus sinicus and rapeseed plants on fertility improvement of soil was also investigated， and economic benefit was worked out. 【Result】Fresh yield of Astragalus sinicus and rapeseed dropped gradually after full-bloom stage， however dry matter content increased. The effect of manure application on soil fertility conditions varied under different application methods. The organic matter content was recorded as the highest（6.6% higher than basic soil）when soil was plowed at the full-bloom stage of Astragalus sinicus. Applying Astragalus sinicus and rapeseeds manure significantly increased the yield of rice, and the highest yield（9244.5 kg/ha）was recorded in Astragalus sinicus plowed at the full-bloom stage. The economic benefit was the highest（6696 Yuan/ha）when the soil was plowed at the maturity stage of rapeseed, with the input/output ratio of 2.49∶1.00. 【Conclusion】The highest increase in soil fertility was observed when the soil was plowed at the full-bloom stage of Astragalus sinicus， while the overall benefits were maximum when fields were plowed at maturity stage of rapeseeds.