The invention discloses a state monitoring system for turning lights and braking lights of an automobile. The state monitoring system consists of a power supply detection part and a light intensity detection part, wherein the power supply detection part consists of a first divider resistor, a photoisolator and a second divider resistor; one end of the first divider resistor is connected with the positive pole of a 24V power supply, and the other end of the first divider resistor is connected with the No.1 wiring end of the photoisolator; the No.2 wiring end of the photoisolator is connected with the negative pole of the 24V power supply; one end of the second divider resistor is connected with the No.3 wiring end of the photoisolator, and the other end of the second divider resistor is connected with the negative pole of a 5V power supply; the N0.4 wiring end of the photoisolator is connected with the positive pole of the 5V power supply; the No.3 wiring end of the photoisolator is also set as an output end U01; the light intensity detection part consists of a photoresistor and a divider resistor; one end of the photoresistor is connected with the negative pole of the 5V power supply, and the other end of the photoresistor is connected with the divider resistor; the other end of the divider resistor is connected with the positive pole of the 5V power supply; and the photoresistor and the public wiring end of the divider resistor are connected with an output end U02.