The invention relates to a sea water desalination tool, in particular to a marine sea water desalination device. A rotary frame can rotate frontward and backward on a base, and therefore in the ship sailing process, a sea water desalination assembly can be conveniently placed in sea water, or the sea water desalination assembly can be conveniently taken out of the sea water; a lifting assembly canvertically move on the rotary frame to adjust positions, and therefore the depth of inserting of the sea water desalination assembly in sea water can be adjusted; a sea water exploring frame can be conveniently dismantled from the lifting assembly, and therefore the sea water exploring frame and the sea water desalination assembly can be conveniently dismantled singly, and fresh water in the seawater desalination assembly is taken out. The rotary frame is hinged with the upper end of the base, one end of a push-and-pull control frame is fixedly connected with the upper end of the rotary frame, the other end of the push-and-pull frame is slidably connected with the base, and the lifting assembly is slidably connected with the rotary frame; the sea water exploring frame is slidably connected with the lifting assembly, and the sea water desalination assembly is fixedly connected with the lower end of the sea water exploring frame.