In order to accurately measure the pulse width of 193 nm deep ultraviolet femtosecond laser, a pulse width measurement system was designed and built based on the two-photon fluorescence effect of calcium fluoride. The square dependent relationship of the two-photon fluorescence signal on incident laser intensity confirms the reliability of the two-photon fluorescence signal. The numerical calibration of the CCD detection system is carried out using insertion method, and the obtained time scale correspongding to a single pixel is 7.35 fs. In single-shot pulse measurement, the pulse width of 193 nm deep ultraviolet femtosecond laser is measured to be 476.1 fs, which is basically consistent with the result obtained through measurement and calculation using spectroscopy.