Lens is the eye of the camera, the quality of lens determined the clearance of images. Except focusing on the selection and design of CCD and DSP circuit, choosing an appropriate lens for security camera is very important to achieve the full features of security camera. Lens consist of one series or muti-series of optical lens, adopts the mechanical structure to form image. Different optical lens combination can form different distance of image. Manufacturers design and manufacture different camera lens to meet the various demands from market. Due to the complex of installation environment, some of security camera installer and security dealer may face problem on the selection of correct camera lens for video surveillance camera. We herein share some information with our own experience.