For the low-voltage user missort fault phenomenon occurred frequently in current supply service, the intelligent detection equipment has been developed which is widely used in the power industry and the electric power construction team to check power lines missort fault of the residential building. This paper describes the necessity of developing the device, put forward the overall design scheme and design principle of the system, respectively set forth the design principles of the master machine and the slave machine, briefly explains the software design process of the master machine and the slave machine, and introduces the operational approach of the master machine and the slave machine. Small wireless communication technology, multi-channel detection technology, wrong wiring comprehensive discriminate technology, master-slave machine man-machine interactive technology, etc have been used in the design. The site comparison test has proved that the equipment can improve the work efficiency and the detection accuracy of the spot inspector, reduce labor intensity, has great application value.