The utility model provides an impact system is prevented to bridge crane master file, this intelligent monitoring system includes: the master file gear limit, PLC system, master file elevation indicator and remote monitering system. The PLC system includes that left wheel comparator, right wheel comparator and high demonstration normally open some modules. The PLC system passes through the cable with the master file gear limit, master file elevation indicator and remote monitering system respectively and links to each other. Using this technique back, having solved bump the easily problem of surface equipment and facility of bridge crane, the safe operation has added the second and has heavily ensured to the crane in the aspect of equipment.