NOVELTY - A filter pressing water electrolyzer comprises anode semi-groove component, cathode semi-groove component, bipolar unit groove component(s) positioned between the anode and cathode semi-groove components and insulating sealing washer. The anode semi-groove component and bipolar unit-groove component of anode chamber is installed with flexible metal or net-shaped main anode weaved by metal wire, net shaped auxiliary anode and anode supporting module, and liquid conducting gridding structure. A diaphragm is installed between the main anode and main cathode.    USE - Filter pressing water electrolyzer is used for producing hydrogen.    ADVANTAGE - The filter pressing water electrolyzer is compact, simple in structure, highly efficient and economical, and has high nitrogen purification.    DETAILED DESCRIPTION - A filter pressing water electrolyzer comprises an anode semi-groove component, a cathode semi-groove component, bipolar unit groove component(s) which is positioned between the anode and cathode semi-groove components and insulating sealing washer. The anode semi-groove component and bipolar unit-groove component of anode chamber is installed with flexible metal or net-shaped main anode weaved by metal wire, net shaped auxiliary anode and anode supporting module with ventilate, and liquid conducting gridding structure having elastic expanding performance. The cathode semi-groove component and bipolar unit groove of cathode chamber is installed with net shaped main cathode weaved by metal or metal wire, net shaped auxiliary cathode, and cathode supporting module with ventilate, and liquid conducting gridding structure having elastic expanding performance. A diaphragm is installed between the main anode and main cathode. The main anode and main cathode comprises flexible foaming nickel, sponge nickel or metal mesh weaved by nickel wire or nickel alloy wire. The auxiliary anode is metal mesh weaved by nickel wire or nickel alloy wire, and the auxiliary cathode is metal mesh weaved by nickel wire, nickel alloy wire or stainless steel wire. The diaphragm is micro-porous film or ionic membrane.