The invention belongs to the technical field of processing and application of MOFs fiber membranes, and particularly relates to an MOFs fiber membrane for adsorbing and intercepting micro-nano plastics in water and a preparation method of the MOFs fiber membrane. The preparation method comprises the following steps: putting a fiber fabric, sodium hypophosphite and tetracarboxylic acid into deionized water, stirring for 1 hour, then taking out the fiber fabric, performing rolling twice at 30MPa, baking at 100 DEG C for 5 minutes, performing cleaning with deionized water, and performing drying to obtain a modified fiber fabric; putting the modified fiber fabric into a mixed solution of a long-chain carboxyl organic ligand and protein for 30 minutes, performing fully swelling, taking out the fiber fabric in a swelling state, putting the fiber fabric into a zinc nitrate solution, carrying out in-situ assembly for 5 minutes, taking out the fiber fabric, putting the fiber fabric into a drying oven, treating the fiber fabric at 60 DEG C for 2 hours, cooling the fiber fabric to room temperature, and obtaining the MOFs fiber membrane. The nano MOFs crystalline particles are distributed in swelling holes of cellulose fibers, and the prepared composite membrane material is rich in holes, huge in specific surface area and capable of efficiently adsorbing and intercepting micro-nano plastics in water.