The invention discloses a circuit breaker switch state detection device based on the principle of a magnetic field. The circuit breaker switch state detection device comprises a magnetic field detection circuit, a single-chip microcomputer circuit, a data uploading circuit, an indicating lamp circuit and a power supply conversion module. The output end of the magnetic field detection circuit is connected with the single-chip microcomputer circuit. The output end of the single-chip microcomputer circuit is respectively connected with the indicating lamp circuit and the data uploading circuit. The power supply conversion module supplies power to the magnetic field detection circuit, the single-chip microcomputer circuit and the indicating lamp circuit. The disconnection state of a circuit breaker is detected by adopting the new parameter magnetic field, and an original detection mechanism can be assisted to judge the state of the circuit breaker so that reliability can be enhanced; the structure of the circuit breaker or the original detection system does not need to be changed; and data storage through a computer and monitoring of the detection result are facilitated for users.