This paper gives the nonlinear analyses of the core 3He nuclear reaction diffusion system. It is shown that the system can be led a sudden change to a new supercritical space structure from the original steady——state after the effects of convection and diffusion are taken into account, and the production rate of 3He changes and the total of its density increases. The 3He may be denser in a limited local region so that the reaction rate of 3He+3He is accelerated to have a high energy generation in the region. The understanding for the solar core is also given.