The invention discloses a detection method for heparin content. The detection method comprises the steps of mixing a sample to be tested with an FXa activity detection reagent by a developing substrate method to obtain a mixture, incubating the mixture, and detecting the signal intensity of a developing substrate; and finally calculating signal intensity and comparing the calculated signal intensity with a standard curve to obtain the heparin content of the sample to be tested, wherein the developing substrate is a developing substrate of an activated factor X (FXa) and is selected from any one of the following substrates of Benzoyl-Ile-Glu-Gly-Arg-p-nitroanilide.HCl, CH3O-CO-D-CHA-Gly-Arg-p-nitroanilide.AcOH, Acetyl-D-Arg-Gly-Arg-p-nitroanilide.2HCl and 4-Nz-D-Arg-Gly-Arg-p-nitroanilide.2HCl. The detection method disclosed by the invention can be used for detecting general non-graded heparin, low-molecular-weight heparin and fondaparinux; furthermore, according to the detection method, the detection stability and the repetitiveness are high, the heparin content can be reflected accurately, the sensitivity and the accuracy are extremely high, and the optimal dosage range of the heparin can be found out quickly, so that a patient does not need to be detected for multiple times. Moreover, the detection method can be also used on an automatic instrument such as a coagulation analyzer or a biochemical analyzer, so that automation is realized, and clinical popularization and application can be assisted; the detection method has the characteristics of simplicity in operation, high sensitivity and high repetitiveness.