API TR 11L, which is recommended by API as a way of design calculation for sucker rod pumping system, is including a series of dimensionless charts and calculation formula. Academic and practical values are shown in these dimensionless charts. The research of performance curves of sucker rod pumping, which are equivalent to those of electric submersible pump (ESP) and progressive cavity pump (PCP), is relatively rare. In API TR 11L, characteristic curve of SRP is implied in those dimensionless curves, subsurface dimensionless characteristic curve of sucker rod pump system can be given by deduction based on present API theory method. When applied for heavy oil wells, deviated wells, low production wells and wells with high gas/oil ratio, the curves of SRP RP 11L should be corrected. In this paper, based on API TR 11L common methods, dimensionless characteristic curve of subsurface system of sucker rod pump and corrected API curves with unconventional conditions have been derived, providing better optimization and analysis methods for suck rod pump wells, enlarging application range of API TR 11L.