Abstract: Based on the fact that interferometric correlation term of femtosecond pulse contains the phase and frequency information, the magnitude information of chirp of femtosecond laser pulse can be obtained by measuring the magnitude and shape of two visual spectra component with surging frequency ?棕?子 and 2?棕?子 inside the autocorrelation second harmony interferometric stripe, and the area and shape of envelope of second interferometric autocorrelation function. Otherwise, through the derivative modified spectrum of autointerferometric correlation(D-MOSAIC) derived from a conventional second order interferometric autocorrelation trace, whose peak and value correspond to the positive and negative chirp, the sine function factor of the determinant chirp direction was obtained. Futhermore, chirp direction of ultrashort laser pulses could be determined. Thus, the chirp characteristics of femtosecond pulse laser could be detected through second order autointerferometric correlation using measurement system meeting basic condition of optics interference.