Abstract: In order to improve the output energy stability of non-chain discharge-pumped pulsed HF laser, the chemical reaction dynamics of the HF laser and key factors determining the output stability were analyzed. The combination of the generation of fundamental-state HF molecules, the rising temperature of gases and the consumption of C2H6 was responsible for the rapid decrease of output energy. Experiments were performed to verify the analysis, from which some conclusions could be drawn as follows. The output energy decreased by as high as roughly 31% of the starting value without eliminating of reaction products (i.e., the fundamental-state HF molecules), whereas the output energy was relatively much more stable with zeolite molecular sieve to adsorb the fundamental-state HF molecules after 1600 output pulses. The output energy decreasing ratio of the latter was only 10% after 5500 output pulses. In addition, temperature recovering of gain medium to the initial state, as well as the supplement of C2H6 into the cavity, was demonstrated to improve the stability of output energy. Quantitatively, supplement of C2H6 by 25% could improve the output energy by 8%. According to the chemical reaction dynamics and experimental results, the output energy stability is supposed to be improved by mounting the zeolite molecular sieve absorber, gases temperature controller and real-time gain medium supplement unit into the HF laser device.