To overcome the effects of eyebrows,eyelashs,shadows,occlusion and noises in traditional integral projection methods,a precise eye localization method based on gradient integral projection and expectation-maximization(EM) algorithm is proposed.Both eye regions and precise eye positions can be detected in facial images by our method.Firstly,coarse eye regions are detected by row gradient integral projection function which is calculated by a novel gradient operator.Then,precise eye windows are detected by fitting two Gaussian distributions to the column gradient integral projection curve of the eye regions by EM algorithm.Finally,a weighted barycenter algorithm is proposed to locate the positions of eyes precisely.Experimental results on our image database and YaleB database demonstrate that our method is more robust to eyebrows,noises and occlusion due to eyelids and eyelashs,and performs well under different illumination conditions and head poses.