The invention discloses a state monitoring system for a vehicle brake lamp. The state monitoring system comprises a photo isolator, an operational amplifier, a direct current transmitter, a current-limiting protective resistor and a brake lamp, wherein one end of a voltage grading resistor is connected with the cathode of a 5V power supply, and the other end of the voltage grading resistor is connected with a pin 3 of the photo isolator; the pin 2 of the photo isolator is connected with the cathode of a 24V power supply; the pin 1 of the photo isolator and the VO end of the operational amplifier are connected with one end of a feedback resistor; the other end of the feedback resistor and the negative end of the operational amplifier are connected with one end of an input resistor; the other end of the input resistor and a No.2 grounding resistor are connected with one end of the current-limiting protective resistor; the other end of the current-limiting protective resistor is connected with the anode of the 24V power supply; the positive end of the operational amplifier is grounded through a No.1 grounding resistor; the brake lamp is connected in parallel between the anode and the cathode of the 24V power supply; the direct current transmitter is sleeved on an electric wire between the anode of the 24V power supply and the brake lamp; and the positive and negative ends of the direct current transmitter are connected with anode and cathode electric wires of a 12V power supply.