The utility model relates to the technical field of unmanned helicopter cruising and discloses an auxiliary control device for preventing an unmanned patrol helicopter from mistakenly hitting a transmission line. The device comprises a base and an FPGA minimum system arranged in the base and also comprises a scanning module, an actuator communication interface, an RF emitting module, an accelerometer, a gyro and a magnetic sensor which are connected with the FPGA minimum system respectively. The structure of the device is simple, and on the basis of not greatly changing an existing GPS navigation unmanned patrol helicopter design, the unmanned patrol helicopter is assisted to precisely avoid the hitting of a transmission line and a tower mistakenly.