Energy calibration of resistive charge division-based position-sensitive silicon detectors is achieved by parabolic fitting in the traditional method, where the systematic variations of vertex and curvature of the parabola with energy must be considered. In this paper we extend the traditional method in order to correct the fitting function, simplify the procedure of calibration and improve the experimental data quality. Instead of a parabolic function as used in the traditional method, a new function describing the relation of position and energy is introduced.The energy resolution of the 8.088 Me V α decay of213 Rn is determined to be about 87 ke V(FWHM), which is better than the result of the traditional method, 104 ke V(FWHM). The improved method can be applied to the energy calibration of resistive charge division-based position-sensitive silicon detectors with various performances. Energy calibration of resistive charge division-based position-sensitive silicon detectors is achieved by parabolic fitting in the traditional method, where the systematic variations of vertex and curvature of the parabola with energy must be considered. In this paper we extend the traditional method in order to correct the fitting function, simplify the procedure of calibration and improve the experimental data quality. Instead of a parabolic function as used in the traditional method, a new function describing the relation of position and energy is introduced. energy resolution of the 8.088 Me Vα decay of213 Rn is determined to be about 87 ke V (FWHM), which is better than the result of the traditional method, 104 ke V (FWHM). The improved method can be applied to the energy calibration of resistive charge division- based position-sensitive silicon detectors with various performances.