The invention relates to a yield determining method, in particular to a method using high performance liquid chromatography to determine the yield of o-aminophenol prepared by using o-nitrophenol. The method includes: standard curves, using peak area as vertical coordinates and concentration as horizontal coordinates, of o-nitrophenol and o-aminophenol are acquired respectively through the high performance liquid chromatography; the high performance liquid chromatogram of the final sample solution of the o-aminophenol prepared by using the o-nitrophenol is obtained by the high performance liquid chromatography; the peak area of the o-nitrophenol and the o-aminophenol are acquired respectively from the high performance liquid chromatogram and substituted into the standard curves obtained in the first step to acquire the concentration of the o-nitrophenol and the o-aminophenol respectively.