In photocathode electron gun system, the space-time shaping of the laser is one of the important parts to achieve low emittance of the beam. Based on the C-band photocathode electron gun test platform of the Southern Advanced Photon Source pre-research project, the layout and testing of the drive laser system are introduced in this paper. A 266 nm laser with an initial RMS pulse length of 160 fs is first used as the driving laser in the test platform in China. The longitudinal time of the laser pulse is shaped by the pulse time delay of the birefringent crystal, and the transverse beam is realized by an adjustable diaphragm with multiple apertures. After shaping, the laser platform can provide a Gaussian pulse with a longitudinal RMS length of 160 fs and 420 fs, and a flat-top distributed pulse laser with FWHM of 5 ps. According to the laser test results, the influence of different pulse distributions on beam emittance evolution and pulse distribution is briefly analyzed in this paper. It provides not only a guidance for the photocathode electron gun commissioning, but also support for further research on the effect of initial pulse distribution on space charge force.