The invention which discloses a membrane polar distance repolarization natural cyclic ionic membrane electrolytic tank relates to an electrolytic device used in chlor-alkali industry and aims at solving the problem that the tank voltage is influenced by the solution voltage drop existing among the electrodes in the prior art. The invention mainly consists of unit electrolytic tanks (2), an end part semi-unit electrolytic tank and a sealing pad and ionic membranes (3) which are positioned between the unit electrolytic tanks; the invention has the design points that a support net (11) of a cathode side is welded on a cathode plate (9) to form a cathode chamber through a cathode side gluten plate (10); the cathode side of the unit electrolytic tank also comprises a cathode net (13) and an elastic net (12) which is welded on the support net of the cathode side while the cathode net is arranged outside the elastic net and a sealing surface of a frame is lapped and fixed around the cathode net; the ionic membranes of and among all unit electrolytic tanks are serially connected through a side rod (1) of an extruder and the cathode, the ionic membranes and the anode are closely connected. The invention has the advantages of more stable running, great resistance to positive-negative pressure difference, low voltage and low electricity consumption.