Through experimental data of total, nonelastic scattering, elastic scattering cross sections, and elastic scattering angular distributions of Sn, a set of neutron optical model potential parameters is obtained. All reaction cross sections, angular distributions, energy spectra, gamma-ray production cross sections, gamma-ray production energy spectra, especially, the double-differential cross section for neutron, proton, deuteron, triton, and alpha emission, and inelastic scattering cross sections and inelastic scattering angular distributions for low-lying residual nucleus states are calculated and analyzed for n + 112,114-120,122,124,natSn at incident neutron energies from 0.1 to 20 MeV based on measured data and the nuclear model theory, which are an optical, semiclassical model of multistep nuclear reaction processes and distorted-wave Born approximation theory. Theoretical calculations are compared with existing experimental data and other evaluated data from JENDL-3.