A detection method for low molecular weight heparin complete degradation products using hydrophilic interaction chromatography and multiple reaction monitoring tandem mass spectrometry. Identifying the original reducing end and non-reducing end of enoxaparin sodium by means of reducing the reducing end of enoxaparin sodium, and performing hydrolysis using hydrogen peroxide. Performing quantitative analysis on all component units utilizing hydrophilic interaction chromatography and multiple reaction monitoring tandem mass spectrometry, in particular quantifying low-content special structures and characterizing low molecular weight heparin.