Cross-polarized wave (XPW) generation is a simple and flexible nonlinear filter for the contrast improvement of ultra-intense femtosecond laser pulse,which could enhance signal-to-noise ratio(SNR) efficiently. The principle of XPW filter is introduced briefly. The results from numerical simulation indicate that the XPW energy conversion efficiency is determined by the angle β between the input polarization direction and its [100] axis,phase modulation (PM),input intensity,crystal length and spatial shape. Among them,PM is the main cause of shorting saturation length and decreasing maximum conversion efficiency. It also reveals that initial quadratic and third-order spectral phase induced XPW pulse shape distortion,spectrum narrowing,central spectral shift of the center and efficiency decline,which provides the theoretical basis for XPW nonlinear filter to enhance ultra-intense and ultra-short pulse effectively.