The invention discloses an internal-pressure detachable double-sealing type membrane separator. The internal-pressure detachable double-sealing type membrane separator is characterized in that a double-sealing type membrane component (1) is arranged in a shell (2); semicircular supporting rings (3) are arranged between the inner sides of two side sealing heads of the double-sealing type membrane component (1) and the shell (2); O-shaped rubber rings (4) are arranged on the two side sealing heads of the double-sealing type membrane component (1); the two side sealing heads of the double-sealing type membrane component (1) are sealed with an end cover (5) by the O-shaped rubber rings (4); the inside of the shell (2) is sealed with the end cover (5) by a gasket (6); the inside of the shell (2) and the outer side of the end cover (5) are clamped by a clamping hoop (7); the shell (2) is also provided with a feed-gas inlet (8), an osmotic-gas outlet (9) and a reminding-gas outlet (10). The internal-pressure detachable double-sealing type membrane separator disclosed by the invention has the advantages that fast installation and disassembly of the double-sealing type membrane component in the membrane separator can be conveniently completed by the semiring-shaped supporting gaskets without damaging the two side sealing heads, so that the cost for replacing the membrane component is effectively reduced.