In this paper a solution of soil-water infiltration under the conditions of rainfall and irrigation is obtained through solving the mathematical model of field soil-water infiltration with the second type boundary. This solution coincides with practical response better than the solution with the first type boundary. And the calculation precision is improved. According to the infiltration test data of Zhaozhou testing ground, the distribution in time and space, the capacity and velocity of soil-water infiltration are calculated and analyzed. It is very important to utilize and manage ratoinally resources of soil, water and fertilizer.