Abstract: The neutron reaction data of ¹³⁹La isotope at neutron energy below 20 MeV were calculated with the distorted wave Bonn approximation (DWBA), as well as the united Hauser Feshbach and the angular momentum and parity dependent exciton model, and the existing optical model potential parameters were used. The data include cross sections, elastic and inelastic scattering angular distributions, and energy spectra and double-differential cross sections for neutron and charged particles. Moreover, resonance parameters were also added in the final data file, and unified adjustments were done to keep the consistency among different reactions. Evaluated data were compared with experimental data and existing evaluations. Finally a new data file was given in the ENDF-6 format.