The invention discloses an ultrashort laser pulse shape measurement device. In the device, a detected vertically-polarized parallel laser beam passes through a light splitter and is divided into transmitted light and reflected light, reflected fundamental frequency light is subjected to beam expanding and then is divided by a biprism into upper fundamental frequency light and lower fundamental frequency light which are parallel to each other and which enter a frequency doubling crystal at symmetric angles, then horizontally-polarized frequency-doubled light is generated, time intensity information is converted into intensity autocorrelation one-dimensional space information, the frequency-doubled light and the transmitted light after the light splitter achieve frequency conversion on a frequency conversion crystal, then third-order correlation signal light is generated, the time intensity information is converted into intensity third-order correlation two-dimensional space information, and finally, pulse shape information is obtained though the simple reconstruction technology. The ultrashort laser pulse shape measurement device is low in cost, compact and simple in structure and convenient to adjust, and can measure picosecond and femtosecond pulse shapes.