The invention relates to a low-voltage distribution cabinet neutral line fracture protection device and a detection method and belongs to the electric power equipment technical protection field. The invention aims to provide the low-voltage distribution cabinet neutral line fracture protection device and detection method which are simple in structure, easy to implement and can assist in quickly judging the fracture condition of a neutral line. According to the technical schemes of the invention, the power source input end of a voltage reduction and rectification circuit is connected with the output end of a load side alternating current voltage; the power source output end of the voltage reduction and rectification circuit is connected in series with a voltage stabilization circuit, and then is connected with the power source input ends of a signal monitoring circuit, a logic judgment circuit and a signal output circuit; the input end of the signal monitoring circuit is connected with the neutral line of the load side alternating current voltage; the output end of the signal monitoring circuit is connected with the first input end of the logic judgment circuit; the output end of the signal output circuit is connected with the second input end of the logic judgment circuit; an execution circuit is connected in series between the logic judgment circuit and the signal output circuit; and the execution circuit is connected with a three-phase linkage circuit breaker.