The invention discloses a multichannel temperature detection system for a high-voltage line single chip microcomputer, which relates to the technical field of temperature detection. A main control chip is mutually connected with a crystal oscillator circuit, a reset circuit and a power indicating circuit respectively; the main control chip is in communication connection with a host computer through a host computer communication serial port; the main control chip is connected with multiple temperature sensors respectively; the main control chip adopts an MCS-51-series microcontroller; the temperature sensor adopts a DS18B20 digital temperature sensor; the temperature sensor is connected with the main control chip by adopting a single bus interface mode; the power indicating circuit is provided with a self-locking button and an LED lamp, and the self-locking button and the LED lamp are serially connected through a resistor; and the main control chip is connected with an anti-backflow circuit, and the anti-backflow circuit is that the MCU_RXD end of the main control chip is connected with a pull-up resistor and a diode. Thus, requirements can be met, scalability is realized, and the cost performance is high.