In order to improve the transmission capacity of the optical fiber communication system, the photonic crystal few-mode fiber is optimized by full vector finite element method. The light field distribution and effective mode field area of stimulated Brillouin scattering(SBS) in the photonic crystal few-mode fiber are calculated, and the influences of pump power on slow light time delay and pulse broadening factor are also simulated. The results show that the SBS threshold decreases with the increase of fiber effective length; Under the same conditions, the SBS threshold of LP01 mode is less than that of LP11 mode, but the slow light time delay of LP01 mode is greater than that of LP11 mode; The slow light time delay and broadening factor of the two modes increase linearly with the increase of the input pump power. Optimizes the input pump power can be obtained that slow light time delay of LP01 mode and LP11 mode are respectively 881 ns and 533 ns, meanwhile the corresponding broadening factors are 1.453 and 1.293 separately.