The invention discloses a method for measuring the content of thiourea in thiourea synthesis by means of an HPLC external standard method. By adopting an Agilent high performance liquid chromatograph 1260, a HILIC chromatographic column is adopted as a separation chromatographic column, an ultraviolet visible absorption detector is adopted, an acetonitrile and ammonium bicarbonate water solution is adopted as a mobile phase, thiourea is adopted as a standard sample, the external standard method is used for drawing a thiourea concentration-peak area standard curve, a standard curve regression equation is obtained, and the content of thiourea is obtained through calculation by means of a regression equation. Raw materials, by-products and products with the similar polarities can be effectively separated, samples do not need to be pretreated, the analysis time is shortened, and the method is simple and easy to implement, convenient to implement and reliable.