The invention provides a CNC cooperative control device and a numerical control system. The CNC cooperative control device comprises a microprocessor, a shaping circuit, a differential circuit and a PWM output circuit, wherein the shaping circuit performs shaping processing on signals output by an external PC computer so as to generate a jitter-free and clear main signal and a spindle motor rotating speed control signal; the differential circuit differentiates the jitter-free and clear main signal into a multipath signal; when an enable signal is received, the multipath signal is output to an external driving motor, the PWM output circuit generates analog voltage to be output to the external driving motor according to the spindle motor rotating speed control signal; the microprocessor monitors the minimum time interval of an MODBUS data packet output by the PC; and when the minimum time interval of the MODBUS data packet output by the PC exceeds a preset threshold value, the enable signal is stopped outputting to the differential circuit, so that the differential circuit stops outputting the multipath signal to the external driving motor.