Abstract: The important parameters and evolution rule of laser plasma can be obtained by diagnosing the laser plasma. Based on the photographs of plasma sparks shot by industrial high-speed CCD under different laser energy levels, the shape, size, color and variation characteristics of plasma were studied. The results showed that plasma plume looked like a liquid-droplet in space and expanded in the opposite direction of the laser beam. With the increase of laser energy, the size of plasma increased greatly in horizontal and vertical directions, and the expand rate slowed down.