Abstract: Field experiments were conducted to study the effects of controlled-release fertilizer on the vertical distribution of soil nutrients and nutrient use efficiencies under the potato and maize relay cropping system. The results indicate that the contents of the soil available N are increased and the leaching amounts of soil available N are significantly decreased under the application of the controlled-release fertilizers. The average content of soil NO3-N under the arable soil layers is decreased by 28.60%, while the apparent recovery efficiency of the applied N is increased by 16.32% in average. Furthermore, the P and K leaching amounts are inhibited to a certain degree, which are decreased by 5.72% and 7.03% respectively in average. As a result, the P and K efficiencies are increased by 8.67% and 10.01% correspondingly. Compared with the conventional treatment of the controlled-release fertilization, the nutrient contents in the arable soil are not significantly decreased under the reduction treatment (80% of the convention treatment). On the contrary, the available nutrient contents in the arable soil are decreased, for example, the content of NO3-N is decreased by 14.36%, and the nutrient use efficiencies are significantly increased, such as the apparent recovery efficiency of applied N is increased by 10.22%. Therefore, the reduction treatment is the optimal treatment based on this experiment. So it was the optimal treatment based on this experiment.