The invention discloses a temperature detecting device and a temperature detecting method. The temperature detecting device comprises a first resistor, a second resistor and a control module, wherein the first resistor is connected with a reference power supply; the second resistor is serially connected with the first resistor, and is parallelly connected with a to-be-detected thermistor; and the control module acquires voltage signals at two parallel ends of the second resistor and the thermistor and two ends of the first resistor, the resistance of the thermistor is calculated based on the voltage signals, and to-be-detected temperature is acquired based on the resistance of the thermistor obtained through calculation. Temperature sensors with an NTC thermistor and a PT100 resistor can be compatible, the circuit design is simplified, the layout space is saved, the processing software is also compatible, and a short circuit detection function is also provided.