Abstract: This paper includes two research contents: 1) Considering the characteristics of drainage fashion in hilly region of South China, a field experiment was conducted to search for the regularity of the concentrations of nitrogen and phosphorus in surface runoff with controlled drainage. The function of total infiltration with time was fit by Philip formula. A multi-objective controlled drainage model was established for storm drainage and reducing nitrogen and phosphorus loss. 2) Based on the Pareto optimal solutions, multi-objective optimization problems were solved by using particle swarm optimizer arithmetic and computer program compiled by MATLAB. Aimed at the characteristics of multi-objective controlled drainage model, the particles fitness, individual extremum and group extremum were defined. The results showed that the computational and observed drainage time were identical, which offered references for farmland drainage management.