This kit is used for quantitative determination of β - hCG in human serum in vitro. Human chorionic gonadotropin (hCG) is a glycoprotein hormone with a molecular weight of 36700 secreted by human placental trophoblast cells. The protein is composed of 37 amino acids, which are α and β subunits. α subunits are the same as FSH, LH and TSH, only β subunits have special structure, and they are covalently linked. The main physiological function of hCG is to maintain pregnancy, including maintaining luteal function, stimulating the production of progesterone and other steroids by luteal cells and trophoblast cells, reducing lymphocyte activity to prevent maternal rejection of fetus. Therefore, the detection of hCG in serum is indispensable for the diagnosis of family planning and related diseases.