Variable underwater curtain self-pre-tightening multipurpose lifting appliance

The invention relates to the field of marine lifting appliances, and particularly discloses a variable underwater curtain self-pre-tightening multipurpose lifting appliance which comprises a lifting seat, an electromagnet and a winding device which are arranged on the lifting seat, a lifting hook assembly consisting of a lifting hook seat and a hook body, a guide part on the lifting hook seat, and a lifting rope connected between the winding device and the lifting hook assembly, and the falling component is provided with a guide-in plate and is sleeved on the lifting rope. The winding and unwinding lengths of the lifting ropes can be changed through the winding device, and certain pre-tightening force can be applied to the two lifting ropes when the two lifting hook assemblies are used for lifting through natural falling of the falling and tightening assemblies during lifting, so that the lifting ropes are tightened; according to the lifting appliance, the two lifting hook seats are arranged on the lifting ro