In order to improve detection efficiency and accuracy of pin parameters, a non-contact measurement method of pin based on subpixel edge localization is presented in this paper. Firstly, LOG operator is used to seek approximate localization on pixel level, which can keep the intact edge information of image while restraining the noise. Then, improved Zernike moment is used to abstract subpixel edge localization. Finally, the exact edge of pin is gained from the discrete subpixel points using the least square fitting method. The experimental results show that this method can locate the edge with high accuracy and good stability, and satisfy the request of the on-line detection of pin.