The utility model discloses a protection device capable of carrying out interlocking control on an out-of-control slide hook of a frequency converter of a hoisting mechanism. The protection device comprises the frequency converter of the hoisting mechanism, an interlocking monitoring device, a brake control loop of the hoisting mechanism and an under-current protection switch, wherein the frequency converter of the hoisting mechanism is connected with the interlocking monitoring device in series; the brake control loop of the hoisting mechanism is connected with the under-current protection switch in series; the interlocking monitoring device is connected with a hoisting brake contactor coil in series. According to the protection device, the interlocking monitoring device is arranged on the frequency converter of the hoisting mechanism to detect output current; the under-current protection switch in the brake control loop of the hoisting mechanism is connected and the interlocking monitoring device acts to control an opening/closing state of the brake control loop of the hoisting mechanism so as to realize the interlocking power-losing protection of a brake of the hoisting mechanism and realize double electric control of the brake of the hoisting mechanism; when the frequency converter is out of control, the brake of the hoisting mechanism is rapidly controlled to avoid safety accidents. The protection device disclosed by the utility model guarantees the safety production.