Abstract: The study aims to find out whether the sustained release urea has certain effects on the disease index of soybean root rot, and whether the effect could be the main factor of the yield decrease. The relationship between the main physiological index of soybean and soybean root rot disease index and yield of soybean was analyzed by using path analysis in 2014. The results showed that the disease index of treatment of long-term sustained release urea was the lowest, which was 33.96% , but its yield was 2998.65 kg/hm2. In the path analysis of the root parameters affecting the yield of soybean, we could see the direct path coefficient was 0.4649, which was the most important factor for underground fresh weight. The disease index of root rot was one of the factors that affect soybean production, but it was not the main factor. The effect of sustained release urea on the yield was mainly through the increase of underground fresh weight.