At different pressure, a pulsed laser was used to irradiate the surface of Hg0.8Cd0.2Te. The emission spectrum from the plasma was detected by a time and space-resolved diagnostic technique. The velocity of the ejected particle was measured on the basis of obtained time of flight spectrum. The experimental results indicate that the velocity of the ejected particle decreases quickly with increasing the distance from target surface. Moreover, the velocity is influenced greatly by the ambient pressure and the laser energy has almost no impact on velocity. In addition, the electron density was estimated by using full width at half maximum and the results show that the electron density decreases quickly during a short period after the laser arrives the surface. Moreover, the maximal electron density emerges at a position which is some distance away from the target surface but not on the surface.