Laser plasma propulsion is a strategic commanding point in the field of aerospace in the future,while the outline evolution of laser plasma has become a necessary condition for laser plasma shock wave propulsion.In this paper,based on the basic theory of the formation of laser plasma,the outline parameters of laser carbon plasma is simulated,then measured under different laser power density by using a Nd∶YAG laser with wavelength of 1.064μmand pulse width of 10 ns and so on.The simulated result is proved by the measured data.In addition,the images taken by a color digital camera show that the evolution procedure of laser carbon plasma can be observed from underdeveloped to fully developed,and then to overdeveloped when the operating voltage of the laser rises from 700 V to 1100 V.Thus the condition for fully developed laser carbon plasma is adjusting the working voltage of laser to 850 V,the average output energy is 157.1 mJ and power density is 4.45×109 W/cm2.As the developed degree of plasma correlates to the propagation and action of laser plasma shock wave,its research becomes an important step to laser plasma shock wave propulsion.