To describe femtosecond laser ablation on metal surface, the double-temperature equation (DTE) was formatted simply. In this paper, numerical simulation for temperature field of femtosecond-picosecond pulse laser ablation on metal surface is performed by finite-difference method (FDM). It is reasonable to make the DTE simple in femtosecond scale. It is also analysed that the effect of electron-lattice couple coefficient g on surface temperature, and found that g determines the surface temperature rising rate and the electron-lattice couple time. Compared with picosecond pulse laser, the intense of pulse is the main factor of the finally temperature of electron. The ablated depth of femtosecond laser can be controlled as thick as the surface depth of metal.