Laser fuze is a kind of proximity fuze generally used in guided weapon. However, it is very difficult to obtain the intensity of reflected laser pulses at the receiver's windows in the laboratory. In addition, testifying the signal processing algorithm in the laboratory is another problem. A method of optical fiber-based simulation system is proposed here for laser fuze. Firstly, coupling lens and auto-focus lens are used in this system to couple the laser beam transmitted from (emitter) into fiber. Then, real-time power attenuation simulation is realized by means of a program-controlled wideband intensity attenuator. After being attenuated, the optical signals returned to windows of receiver through coupling lens by fiber optic propagation. In the system , the fiber is used to propagate laser pulses, so it can accurately simulate the reflective laser signalwhich laser fuze has transmitted such as passing across the target. At the same time, it can testify the signal processing algorithm used in laser fuze in the laboratory through controlling attenuation of laser signal in real-time.By theoretical analysis,system composition and detailed design of every part are proposed,then the design is verified by conclusion.