Basing on measuring the luminescence spectra at room temperature pumped by 975nm light, the action mechanism of Na+ in the novel Yb3+,Na+:CaF2 crystal was systemically investigated. The relation between the concentration of doping Na+ and the laser operation threshold was analyzed. The optimum match concentration for Yb3+,Na+:CaF2 with low laser threshold was obtained. In the experiment, the lowest laser operation threshold at only 70mW of absorbing pumped power for 2%Yb3+, 3%Na+:CaF2 crystal is realized, which is in good agreement with the analysis of luminescence properties.