In order to meet output parameters, especially the stability of the laser energy requirements for the 308 nm skin therapeutic apparatus, first of all, the laser energy attenuation model and proportional integral (PI) algorithm based on energy compensation by the excitation voltage were established, its theoretical analysis and simulation were compeleted. Secondly, the experimental research on excimer laser was carried out which included high voltage excitation power supply and laser energy detection module based on fast nondestructive photoelectric diode. Meanwhile, the experimental research on the relationship between excitation voltage and output power, characteristics of laser energy attenuation and laser energy stability properties with the introduction of PI algorithm was studied. The results show that the power supply and energy detection module meet the PI algorithm control precision and response speed. Meanwhile, the excimer laser output energy can still maintain a target energy within 17.5 mJ and energy variance is slowly rising from 0.2% to 3% in the 10 million pulses after introducing the PI algorithm, which well meets the usage requirements of excimer laser skin therapeutic apparatus.