We present an experimental set up and the calculation approach for the measureme n t of the spectral phase of femtosecond laser pulse by using a spectral phase int erferometry for direct electric reconstruction (SPIDER) technique in this paper, the method for determining crucial parameters as Ωand τwas given. W ith the femtosecond laser pulse from the Ti:sapphire laser, we obtained the phase of the laser spectrum by using the SPIDER, the temporal profile of the original laser pulse was deduced based on the result. It reveals the FWHM width is 107fs, which is in good agreement with the result measured directly by using an autocorrelat or.