The invention provides a detection circuit for the working state of a PTC heating air blower of a new energy vehicle, comprises a speed regulating switch, wherein one end of the speed regulating switch is grounded, and the other end is connected with a speed regulating current limiting resistor which forms a complete closed loop with the positive pole of the power supply through a blower motor, wherein a safety is arranged between the blower motor and the positive pole of the power supply, and current detecting devices and output signals are connected at either end of the blower motor. The speed regulating current limiting resistor is connected with the positive pole of the power supply through a blower motor. The structure is applied to new energy vehicles such as pure electric vehicle (EV), hybrid electric vehicle (HEV), hybrid electric vehicle (HEV) and so on. When PTC heater works, it solves the problem of not detecting the working condition of blower supply system. A current detecting device is used in the invention to detect, and the output signal can be a switching quantity or an analog signal. The output signal is outputted to the vehicle controller VCU of the new energy vehicle or sent to the separate control ECU of the air conditioning system for easy diagnosis and alarm.