Abstract: To predict the poisoning quickly and precisely, a method to determine the parameters of the single group point reactor model with appropriate boundary conditions is developed, and the poisoning is predicted with the single group reactor model. And then,  the evolution of Xenon poisoning and Samarium poisoning is simulated in several working conditions of the reactor of a M310 Nuclear Power Plant with the single group point reactor model. Xenon poisoning and Samarium poisoning calculated by the single group point reactor approximation fits well with the results of a more accurate 3- dimensional 2 group method. The accuracy of the point group model is examined by simulating the Xenon poisoning and Samarium poisoning in a real license operation event. The reactivity worth of Xenon poisoning and Samarium poisoning simulated by the model fits well with the reactivity worth obtained in the experiment. This work shows that the single group point reactor model can illustrate the Xenon poisoning and Samarium poisoning with significant accuracy with the parameters deduced by this method.