The invention relates to a method for evaluating the reducing capacity of reducing agents, and in particular relates to a method for evaluating the reducing capacity of the reducing agents which can be used for reducing ferric iron into ferrous iron. The method comprises the following steps: a, respectively gradually dripping different reducing agent liquids into respectively independent comparison reagents which gradually become colorless along with dripping of the reducing agents, and obtaining the consumption amount of all the reducing agents when the comparison reagents become completely colorless, wherein the comparison reagents are mixed solutions formed by uniformly mixing a ferric ion solution and an ammonium thiocyanate solution till the mixed solutions become red; and b, according to A=reducing agent consumption/Fe2O3 content, testifying that the smaller the A is, the higher the reducing capacity is, wherein the content of Fe2O3 is the mass of Fe2O3 in the ferric ion solutions in the comparison reagents. The method is simple, practical, and strong in maneuverability and can relatively well guide the selection of economical and reasonable reducing agent species.