With respect to the exciton moving in the two-dimensional quantum well, the paper presents a scheme which can rigorously calculate out the binding energy of the exciton in the two-dimensional semiconductor quantum well by simply using the relation $\left|z_e-z_h\right|=\rho \tan \alpha$, which is much simpler than the complex calculation of Ref.[1-2]. Concerning the calculation result eq.(13), the paper discusses the results for two significant cases of $\left|z_e-z_h\right|$<<$\rho$and $\left|z_e-z_h\right|\to \infty$.