We point out that the simplified calculations in the textbook on the scattering of charged particles by the field of a magnetic monopole and the quantization of electric charge lead to some obvious error. Reexamination of the orbit of the charged particle yields the physical picture: the azimuthal angle  as well as the polar angle θ of the incident particle change after scattering. In particular，for very large impact parameter，the change of  is approximately ±π/2. The change of the angular momentum is calculated and reasonable results are obtained. The scattering cross section is also discussed.