We propose a fast testing method based on an oversampling model to meet the demands for rapid modulation transfer function detection in low-light level CMOS image sensors. This method optimizes the inclined edge technique to enhance its accuracy. The testing procedure employs an adaptive dual-threshold Canny edge detection algorithm to enhance edge detection precision. Geometrically rotating the edge angle space oversamples the edge extension response, and we accomplish fitting using the cubic Fermi function equivalent model. This approach significantly mitigates the influence of noise on testing outcomes during natural low-light imaging. When applying this method for practical CMOS sensor testing, we compared the experimental results with the standard values using various target images, and errors remained within 0.06. These findings validate the feasibility and effectiveness of this method, fulfilling the requirements for CMOS sensor performance assessment.