Abstract: Proposing a model of autocatalytic reactions,this paper demonstrates the critical point as a joint of second order like transition line and the first order like one existing in nonequilibrium system. The comparision of this point with the "critical point of phase trasition of second kind" predicted by Landau shows a closed resamblance in their behavior, but also some difference between them. The configurations of critical exponents of these two critical points differ from one anther, though both of them satisfy the same scaling laws.