The invention discloses an underfilled magnetic liquid 
shock absorber adopting a first-order 
buoyancy principle, belongs to the field of vibration in 
mechanical engineering, and successfully solves the problem that an existing magnetic liquid 
shock absorber cannot be applied in 
engineering practice due to many structural problems. The device comprises a base (1), an annular permanent 
magnet (2), a shell body (3), nuts (4), a sealing ring (5), a 
washer (6), a magnetic liquid (7), a first circular permanent 
magnet (8), an end cover (9), a 
mass block (10), a cavity (11), a second circular permanent 
magnet (12) and bolts (13), wherein the shell body is not completely filled with the magnetic liquid (7); the non-magnetic 
mass block (10) moves in the shell body (3), and generates friction, collision and viscous shearing with the magnetic liquid (7) to consume energy in the case of external vibration; and an electrical 
eddy current is generated in the 
mass block (10) to accelerate consumption for the vibration energy and achieve the purpose of shock absorption when the mass block (10) is made from a conductor material.