The invention provides a cefamandole nafate refining method. The method comprises the steps of A, dissolving polyvinylpyrrolidone in a lower alcohol and water mixed solvent to prepare a polyvinylpyrrolidone solution of 0.1-1.0 mol/L, then adding a cefamandole nafate crude product, increasing temperature to 50-80 DEG C, adding activated carbon after complete dissolution, conducting stirring for 10-30 min, and then conducting filtration to obtain a filtrate for use; B, adding sodium iso-octoate of 15% to the filtration obtained in the step A dropwise, and regulating pH to 6.0-7.0, so that a cefamandole nafate crude product solution is obtained; C, adding acetone to the cefamandole nafate crude product solution obtained in the step B dropwise while stirring, then conducting ultrasonic treatment for 10-30 min, continuing to add acetone, conducting stirring at indoor temperature for 1-2 h to enable a large number of crystals to be separated out, conducting filtration, conducting washing with a small amount of ethyl alcohol, and conducting vacuum drying so that a cefamandole nafate refined product can be obtained, wherein the amount of acetone added at the second time is 0.8-1.2 times that of acetone added at the first time. The refining method has the advantages that yield and purity are high, and the product is high in stability and light in color.