The invention discloses a method for preparing a tubular micro-porous filter membrane. The method comprises the following steps: (1) preparing a base membrane casting solution, namely mixing a polymer, an additive and a solvent until each component is completely dissolved, standing in vacuum, and defoaming, thereby obtaining the base membrane casting solution; (2) preparing a separation layer casting membrane solution, namely mixing a polymer, an additive and a solvent until each component is completely dissolved, standing in vacuum, and defoaming, thereby obtaining the separation layer casting membrane solution; (3) preparing a base membrane, namely coating by placing the base membrane casting solution prepared in the step (1) and a non-woven fabric on a tubular coating machine, thereby obtaining the base membrane; and (4) preparing the tubular micro-porous filter membrane, namely putting the separation layer casting membrane solution prepared in the step (2) on the tubular coating machine, uniformly coating the inner surface of the base membrane prepared in the step (3) with the separation layer casting membrane solution to form a polymer seepage filter layer with concentration gradient, standing in air, immersing in a coagulating bath, and performing phase inversion separation. The prepared tubular micro-porous filter membrane is uniform in thickness, uniform in pore size distribution and complete without defects.