The present invention provides an AGC controller performance detection method and device. An AGC controller is connected with an upper computer and a plurality of wind turbine sets. The detection method includes the following steps that: instruction receiving time t1 of the AGC controller by receiving a power instruction from the upper computer is recorded; three-phase current values and three-phase voltage values which are generated by the wind turbine sets by responding to the power instruction are obtained; an active power value P2 is calculated and recorded according to the three-phase voltage values and the three-phase current values, and a current slider effective value is calculated through using a current slider effective value algorithm; response time t2 when the active power output of the wind turbine sets achieves a steady state is calculated; the total response time T1 of the AGC controller is calculated according to the response time t2 and the instruction receiving time t1; the control precision CA of the AGC controller is calculated according to the active power value P2 and an initial power value P1; and whether the AGC controller meets performance index requirements is detected according to the total response time T1 and the control precision CA.