There are many factors that affect the measurement accuracy of the radius of curvature (ROC). So, high-precision measurement of the ROC has been one of the problems in optical measurement. In order to realize high-precision ROC measurement, a method to reduce the measurement error by environment compensation and improving alignment accuracy is presented. Firstly, the main factors that affect the measurement accuracy of the ROC are analyzed theoretically. And then a method for reducing the measurement errors in the measurement process and the corresponding compensation is proposed. Based on the theoretical analysis, typical convex and concave optical parts are measured respectively by interference method which is composed by a Fizeau interferometer and a high-precision displacement measurement interferometer in high-precision laboratory. Experimental results show that the measurement reproducibility is less than 0.2 mm and the relative errors of the measurement are 0.67×10-6 (2s) and 0.60×10-6 (2s) respectively through environment compensation and improving alignment accuracy. The high-precision ROC measurement is realized.