The invention discloses a variable-frequency motor protection device based on intelligent sensors. The variable-frequency motor protection device comprises an electric motor neutral point intelligent sensor, a frequency converter outlet side intelligent sensor, an electric motor power supply side intelligent sensor, a protection device, a communication processing module, a sampling synchronization module, a protective calculating module and respective digital communication channels; current on each side of an electric motor is sampled by the intelligent sensor on each side; and the communication processing module receives sampled data of each side by each digital communication channel, the sampling synchronization module carries out synchronous processing on the sampled data and the protective calculating module utilizes the synchronized data to carry out protective calculation and protective logic judgment. Due to the adoption of the technical scheme disclosed by the invention, the protection of the full-operating working condition of the variable-frequency motor can be implemented by one device, the structure of the device is simplified, the volume and the size of the device are reduced, and the variable-frequency motor protection device is suitable for being arranged in a power supply side switch cabinet. Moreover, the device is simpler to debug and is more comprehensive to self-check.