Summary: If a partial differential equation is reduced to an ordinary differential equation in the form \(u'(\xi)= G(u,\theta_1,\dots,\theta_m)\) under the traveling wave transformation, where \(\theta_1,\dots,\theta_m\) are parameters, its solutions can be written in the integral form \(\xi-\xi_0=\int \frac{du}{G(u,\theta_1,\dots,\theta_m)}\). Therefore, the key steps are to determine the parameter and to solve the corresponding integral. When \(G\) is related to a polynomial, a mathematical tool named complete discrimination system for a polynomial is applied to this problem so that the parameter scopes can be determined easily. The complete discrimination system for a polynomial is a natural generalization of the discrimination \(\Delta=b^2-4ac\) of the second degree polynomial \(ax^2+bx+c\). For example, the complete discrimination system for the third degree polynomial \(F(w)=w^3+d_2w^2+ d_1w+d_0\) is given by \(\Delta= -27(\frac{2d_1^3}{27}+ d_0- \frac{d_1d_2}{3})^2- 4(d_1- \frac{d_2^2}{3})^3\) and \(D_1=d_1- \frac{d_2^2}{3}\). In the paper, we give some new applications of the complete discrimination system for polynomials, that is, we give the classifications of traveling wave solutions to some nonlinear differential equations through solving the corresponding integrals. Finally, as a result, we give a partial answer to a problem on Fan’s expansion method.