The invention relates to an electromagnetic shielding cabin door false locking preventing device, composed of a cylindrical pin, a handle, a screw thread insert, a pressure spring and a bolt. The device is connected with a three-pin lock of a shielding cabin door, the sleeve in the three-pin lock is provided with a false locking preventing device mounting hole, the mounting hole is vertically penetrated with the key cylinder rod of the three-pin lock, the head part of the mounting hole is a screw thread hole, the pressure spring is sheathed in the bolt and then is mounted in the mounting holewith the screw thread insert, the upper end part of the screw thread insert is provided with a groove, the lower end of the bolt is provided with a notch corresponding to the key cylinder rod of the three-pin lock, the other end stretches out the end part of the screw thread insert, the handle is arranged at the stretching end of the bolt and is arranged in the groove at the end part of the screwthread insert, and the handle is fixed with the bolt by virtue of the cylindrical pin. According to the invention, when the electromagnetic shielding cabin door is closed and is falsely locked, the three-pin lock can be unlocked from inside, thus avoiding safety accident and improving safety of device. The invention has the advantage that structure is simple and reliable.