A copper alloy double-internal-thread coupler isolation sea water desalting device comprises a filter suction pipe, a water lift, a pretreatment device, a high pressure pump, a speed increaser, an anticorrosion alloy coupler, an entertainment working device, a reverse osmosis membrane component and an activated carbon adsorption tank, wherein the anticorrosion alloy coupler comprises a left internal thread connector and a right internal thread connector; a filter screen with the spherical radius of 1.2-1.4m is arranged at the bottom end of the filter suction pipe; the upper end of the filter suction pipe is connected with the water lift; a water outlet end of the water lift is connected with the pretreatment device; a water outlet end of the pretreatment device is connected with a high pressure pump water inlet pipe of the high pressure pump; a high pressure pump water outlet pipe is connected with an osmosis membrane inlet of the reverse osmosis membrane component; an osmosis membrane outlet is connected with an inlet of the activated carbon adsorption tank; a drive shaft of the high pressure pump is connected with an output end of the speed increaser; an input end of the speed increaser is connected with the left internal thread connector of the anticorrosion alloy coupler; the right internal thread connector of the anticorrosion alloy coupler is connected with a working output shaft of the entertainment working device; and a rotating handle is arranged on the entertainment working device.