A numerical simulation of recent experimental results of the raman free-electron laser in Shanghai Institute of Optics and Fine Mechanics, has been made by using CAGFEL code which is based on the single particle theory. The calculation shows that when electron energy Ee=0.5MeV, energy spread Δγ/γ=6% and emittance ε=-0.06π·rad·cm, the peak power of the device will be as high as 24MW with a radiation grewth rate of 120 dB/m and a efficiency of 6.1%. The calculation is useful for the overall experiment of Raman free-electron laser.