The invention discloses a method for measuring content of inorganic nitrogen in soil, which comprises the following steps: 1) leaching, namely adding leaching liquor into a soil sample to leach tric nitrogen and ammonium nitrogen in the soil, and filtering to obtain filtered fluid; 2) oxidization, namely adding an oxidizing agent into the filtered fluid obtained in step 1) to oxidize the ammonium nitrogen into tric nitrogen so as to obtain soil total tric nitrogen solution; and 3) performing colorimetric determination with double wavelength on the soil total tric nitrogen solution, and calculating the content of the inorganic nitrogen in the soil according to extinction values obtained by color comparison. The content of inorganic nitrogen in the soil measured by the measuring method has no significant difference with a result measured by a conventional component measurement addition method, and the inorganic nitrogen measured by the measuring method has the recovery rate between 98.8 and 104 percent. The measuring method has the advantages of quickness, accuracy, convenient operation and high efficiency.