Underwater experimental equipment laying and recovery device and method capable of adjusting weight buoyancy

The invention provides a device and method for laying and recovering underwater experimental equipment with adjustable buoyancy, and the device comprises a lifting tool module, a lifting guide module, an experimental frame module, a lifting rope, and a load rejection counterweight module. When the experimental equipment is detected to land on the seabed, lifting equipment on the sea surface pulls a lifting beam module to translate towards the seabed at one side of the experimental frame; the hoisting guide module and the hoisting rope move to the seabed from the two sides of the experiment frame along with the hoisting cross beam module, and the laying process is completed; when the experimental device needs to be recycled, the hydraulic rod of the load rejection counterweight module drives the sliding block to move outwards to be far away from the counterweight block, the counterweight block and the anti-settling cylinder are separated from the experimental device, and load rejection is completed; hoisting e