An improved hybrid projection function (IHPF) for precise eye location is presented in this paper. This algorithm combined the advantage of variance projection function (VPF) and hybrid projection function (HPF) by optimizing their weights in the traditional integral projection function (IPF). Two different face databases, BioID face database downloaded from the internet and PSFace database established by our laboratory, were used to test the influence of different projection functions on correctness and relative mean-error of eye locations. The results show that IHPF with optimized proportion factors has a high eye location correctness of 96~100% and the lowest relative error with better face feature location capability.