Improved hill climbing algorithm is adopted in order to improve the subpixel positioning effect of micro-parts. Firstly, the focusing window is obtained by expanding the target area outward, which tracks the drift image, the boundary is determined by image distance and view angle. Secondly, the optimal convergence solution is obtained by using the optimized hill-climbing search algorithm, two-dimensional image information entropy is constituted by the focusing image evaluation function. Thirdly, modulus of higher moment of improved Zernike moment algorithm replace the edge parameters, which cut the computation amount. The convolution window matrix of difference of Zernike moment is constructed to improve the positioning accuracy. Finally, the flow of the algorithm is given. The experimental results show that the Zernike moment-even template has smaller subpixel positioning error than odd template edge method does, the improved hill-climbing algorithm is decreased by 43.24%,21.62%,32.43%,27.03% and 56.76% respectively compared with spatial moment algorithm, polynomial fitting algorithm, Zernike moment algorithm, region growing algorithm and template matching algorithm about the mean of positioning error of regular shape; the improved hill-climbing algorithm is decreased by 39.02%,21.95%, 26.83%,24.39% and 51.22% respectively compared with spatial moment algorithm, polynomial fitting algorithm, Zernike moment algorithm, region growing algorithm and template matching algorithm about the mean of positioning error of irregular shape. The positioning accuracy of the improved hill-climbing algorithm is higher.