Abstract: In order to improve the primary frequency regulation response capability of thermal power units, DCS operation data were used to analyze key variables during frequency disturbance, including grid frequency, active power, valve opening, main steam pressure, DEH command and AGC command. Based on a typical disturbance process, response delay time, maximum load variation, load change rate and stabilization time were extracted to evaluate the primary frequency regulation performance. The main causes of insufficient response were analyzed, and optimization measures were proposed from the aspects of parameter setting, DEH valve response optimization, and coordinated control of AGC and CCS. The results show that after optimization, the response delay time is reduced from 8.2 s to 4.6 s, the maximum load variation increases from 12.5 MW to 17.8 MW, and the qualified rate of primary frequency regulation increases from 86.0% to 95.5%. The response speed and operation stability of the unit are effectively improved.