Herein, copper ion doped calcium alginate (Cu2+/CaAlg) composite hydrogel filtration membranes were prepared by using natural polymer sodium alginate (NaAlg) as raw material. The thermal stability and structure of the composite membranes were characterized by thermogravimetric analysis and infrared spectroscopy. The mechanical strength, anti-fouling performance, hydrophilicity and filtration performance of the membrane were studied. The results show that Cu2+/CaAlg hydrogel membrane has excellent mechanical properties and thermal stability. The anti-swelling ability of the membrane was greatly enhanced by doping Cu2+. After three alternate filtration cycles, the flux recovery rate of Cu2+/CaAlg hydrogel membrane can still reach 85%, indicating that the membrane has good anti-pollution performance. When the operation pressure was 0.1 MPa, the rejection of coomassie brilliant blue G250 reached 99.8% with a flux of 46.3 L m 2 h 1, while the Na2SO4 rejection was less than 10.0%. The Cu2+/CaAlg membrane was recycled after 24 h in the filtration process, and its flux and rejection rate did not decrease significantly, indicating that the hydrogel membrane has long-term application potential. The Cu2+/CaAlg membrane has a wide range of applications prospect in dye desalination, fine separation and biopharmaceutical technology fields.