Abstract: Aiming at the insufficient coordination between primary frequency regulation and AGC of thermal power units under new energy output fluctuation, this paper takes the DCS operation data of a 1000 MW thermal power unit as the basis. Grid frequency, active power, AGC command, DEH primary frequency regulation command, valve opening and main steam pressure are selected to analyze the response characteristics during typical frequency disturbance. Combined with the field control logic, the parameters of primary frequency regulation, AGC reverse regulation limitation and DEH/CCS coordination mode are optimized. The results show that the response delay time is shortened from 9.6 s to 4.1 s, the maximum load variation is increased from 8.4 MW to 13.7 MW, the reverse regulation times of AGC are reduced from 5 to 1, and the qualified rate of primary frequency regulation is improved from 86.7% to 96.5%. The coordinated control effect is significantly improved.