The principal way of efficiency improvement of solar pumped gas lasers has been considered. CO2-laser with black body reradiator was under investigation. Optical selectivity of reradiator was included into this model and computer simulation shown sufficient efficiency increasing of a solar energy conversion to lasant energy. The usage of selective coating of reradiator is able lo provide some percent efficiency for case of CO2-laser with theoretical limit near 10% (ideal selective coating).