The utility model provides a mounting structure of prefabricated bench is connected to pin key, its constitution includes: bench body, round pin shaft hole, lifting hook, landing slab, ladder beam, the bench body is installed between upper and lower two ladder beam be equipped with the hole for hoist on the step of bench body bench body side is equipped with a set ofly the lifting hook, each division has a set ofly on the step at bench body front and back both ends the round pin shaft hole, ladder beam is the L type ladder beam embeds there is the pin key, round pin shaft hole cover is in on the pin key the strengthening rib is passed through to the vertical direction of pin key will ladder beam with the bench body is fixed pour CGM grout material in the round pin shaft hole. The beneficial effects are that: the utility model discloses the nodal connection atress is reasonable, and the process is simple, and prefabricated bench is connected with cast -in -place ladder beam adoption pin key, CGM grout material is caulked, belongs to the flexonics category, and connected node ductility is high, and construction process is simple, and the quality is easily controlled.