A kind of cubic press cooling power control method was put forward to improve the precision of diamond's temperature. Threewire RTD temperature acquisition circuit with precision up to 05%, impulse signal sampling circuit of turbine flow meter and stepping motor drive circuit were designed. Stepper motor deceleration motion and highaccuracy survey of pulse frequency were realized on the STM32 platform. By using the incremental dead zone PID algorithm, good control effect of constant power cooling was gained.