A modified 2 MeV injector was used to study the photocathode for linear induction accelerators, which adopted a frequency-quadrupled Nd:YAG laser (266 nm) and a quartz window. Its trigger system was improved to realize output synchronization between the pulsed power system and the laser. A scandate cathode was investigated and the maximal cathode temperature was about 740 ℃ in the experiments. Photoemission and plasma emission caused by laser were observed. The maximal laser power density was about 1.3 MW/cm2, the maximal emission current density was about 16 A/cm2, and the quantum efficiency of photoemission was about 0.05‰.