The experimental studies of photocathode driven by a laser are reported in this paper. The experimental systems including the D-C voltage vacuum chamber and measurement apparatus are given. Also we will present the experimental results and discussions of LaB6, pure metals (Cu,Sm) and Cs2Te semiconductor photocathode. The quantum efficiencies of photocathodes are 6 10- 4、3.8 10- 4、11.6 10- 4 and (2~6) 10- 2, respectively, the corresponding photocurrent densities of 70A/cm2、50 A/cm2、102A/cm2 and 57A/cm2 are obtained. Using the pepper pot method, the normalized beam emittances for these materials are about 10p mm· mrad and the corresponding normalized brightnesses are about 1010A/m2× rad2.