The configuration and principle of the temporal profile measurement system are introduced, which are used for multi-beam infrared laser of the high power laser facility. The system is composed of sampling and coupling, fiber transmission, multiplexing coupler, photoelectric conversion and data acquisition unit. The reduced beam and optics imaging method are adopted in sampling of optical fiber in order to solve the problem of the great drift of beams. Because of the laser beam of sinusoidal frequency modulation, the influence of the temporal profile on measurement is systematically evaluated. Optical aberration caused by diagnostic system, the temporal characteristic of different regions, and the bandwidth of sensor are analyzed experimentally and theoretically. The experimental results show that the measurement system of temporal profile based on optical fiber can provide the profile of integral entirely beam of frequency modulation, and monitor the profile reliability.