Precise guidance weapons have given a new concept to the modern warfare,laser-seeking guidance weapons are the key equipment among them. And laser seekers are the important part of laser-seeking guidance weapons,they are the object of continuous development of the world military powers. In this paper,based on the introduction of the guiding principles and characteristics of active and semi-active laser seekers. State-of-art of key technological issues of laser seekers is systematically combed. And it is pointed out that the laser seeker will develop towards the direction of increasing anti-interference ability,multi-mode compound,miniaturization and strapdown.