Abstract: Based on the theory of degenerate four-wave mixing transient grating diffraction, an ultraviolet single shot autocorrelator was set up for resolving the problem confronted in the measurement of ultraviolet pulse laser. The autocorrelator was applied to the measurement of Ti:Sappire second-harmonic-generation laser and third-harmonic-generation laser and KrF excimer laser. The results show that the autocorrelator can acquire the pulse duration in real time and in single shot pattern, present the pulse duration change and the pulse shape modulation, and run within the spectrum range of 248-400 nm and the time range of 5 ps.