The rapid development of precision agriculture has given rise to the innovation of rapid soil sampling technology.Yet the research in the soil sampling head is still absent,which is important in sampling effect and efficiency.Based on the mechanical modeling of the sampling head of soil sampling device on tractor,and aimed at the problem in clayey soil sampling,this paper analyses the resistant force by the soil and internal stress of the sampling head under the working condition of spiral rail.Then a topology optimized mechanical method is found through lots of mathematical and physical calculation and data searching,which has been simulated and calculated by matlab.With the improved shape and geometric parameters from the simulation and calculation,the sampling head is optimized in adhesion decrease,resistance reduction and perfomance of soil removal.And the sampling head has longer service life after optimization.All the virtues have been confirmed by the practical use of soil sampling.