The invention relates to a determining method of an atorvastatin calcium related substance. The method comprises the following steps of 1, preparing a test solution, i.e. taking a proper amount of atorvastatin calcium, adding a solvent to dissolve and quantitatively dilute the atorvastatin calcium until about 1mg of atorvastatin calcium is contained in 1ml of solution, and taking the solution as the test solution; 2, preparing a mixed reference substance solution, i.e. weighing a proper amount of reference substances of an impurity A, an impurity B, an impurity C, an impurity D and an impurity E, and a proper amount of reference substance of the atorvastatin calcium, adding the solvent to dissolve and quantitatively dilute the reference substances until about 3 micrograms of impurity A, 2 micrograms of impurity B, 2 micrograms of impurity C, 2 micrograms of impurity D, 2 micrograms of impurity E and 10 micrograms of atorvastatin calcium solution are contained in 1ml of solution, and taking the solution as the mixed reference substance solution; 3, performing HPLC (High Performance Liquid Chromatography) analysis, i.e. taking 20 microliters of test solution and 20 microliters of mixed reference substance soulution, respectively filling the test solution and the mixed reference substance into a liquid chromatograph, recording a chromatogram until a gradient elution program is finished, and according to the peak area of the chromatogram, calculating the content of each component.