A complete set neutron cross sections, elastic scattering angular distributions, double differential cross sections, γ production data as well as the charged particle emission cross sections of n+~(239)pu reaction in the energy region up to 20 MeV were calculated. Pretty good theoretical results in agreement with the experimental data were obtained and they are comparable with those given by ENDFB-6 and JENDL-3 libraries. A complete set of neutron cross sections, elastic scattering angular distributions, double differential cross sections, γ production data as well as the charged particle emission cross sections of n + ~ (239) pu reaction in the energy region up to 20 MeV were calculated. Pretty good theoretical results in agreement with the experimental data were obtained and they are comparable with those given by ENDFB-6 and JENDL-3 libraries.