The utility model discloses an inverted -siphon formula two -way staircase formula ship lift of passing a bridge, including inverted siphon, at the inducer and an inverted siphon export section upside at inverted siphon import place, build upper reaches checkdam and low reaches checkdam respectively, the orbital segment is located between two checkdams in the transition pond, is equipped with the ship reception chamber on the orbital segment, still includes guide pulley group, and the preformed hole that passes the linkage segment through wire rope is connected with the ship reception chamber of upper reaches checkdam or low reaches checkdam homonymy, the navigation demand of realization upstream and downstream ship. The utility model discloses combine together inverted siphon with two -way ship lift, can make the ship current under the condition that does not influence bridge structures and operation. Can satisfy the demand of passing a bridge of small -size ships such as boat, bamboo raft, drift ship. Simple structure effectively reduces the construction investment, and the electric power of using manpower sparingly improves the ship and crosses dam efficiency. This is in the mountain region area inconvenient remote river of power supply to those, and the meaning is more outstanding.