Time-resolved reflectivity changes of crystalline silicon surface on a 50-ps time scale have been measured using the femtosecond (λ=800 nm) pump-probe technique, and the ultrafast carrier dynamics are also investigated. Time-resolved reflectivity changes can be well described by the reflectivity model which is based on the time evolution of free carrier density. This implies that the ultrafast response of reflectivity is dominated by the excited free-carrier contribution. Then the surface recombination velocity (SRV) value S=1.2×106 cm/s is extracted. A self-consistent carrier transport model is established to simulate the time evolution of carrier density and temperature. The results show that surface recombination plays a critical role in the response of carrier dynamics in intrinsic crystalline silicon surface.