调制传递函数(MTF)是反映航天光学遥感器成像性能的重要参数。刃边法是测试MTF一种简单有效的途径,快速傅里叶变换因计算量小在刃边法中得到了广泛应用。由于线扩展函数在空间域是无限连续的信号,而快速傅里叶变换处理的有限长离散序列,对线扩展函数应用快速傅里叶变换时需先对其截断、采样;截断引起频谱泄露,采样造成频谱混叠,泄露与混叠双重效应将导致最终MTF的测量误差。文章基于采样理论,定量分析了线扩展函数截断区间和采样间隔对奈奎斯特频率处MTF的影响。针对不同应用和误差要求,给出了合理的采样间隔、截断区间要求,规范了快速傅里叶变换在刃边法测量光学遥感相机MTF中的应用。 Modulation Transfer Function (MTF) is an important parameter that reflects the imaging performance of aerospace optical remote sensors. Edge-edge method is a simple and effective way to test MTF. Fast Fourier transform is widely used in the edge-edge method due to its small computational complexity. Since the linear expansion function is an infinitely continuous signal in the spatial domain and a finitely-long discrete sequence processed by the Fast Fourier Transform, it is necessary to truncate and sample the linear expansion function when it is applied to a fast Fourier transform. The truncation causes spectral leakage, Sampling causes spectral aliasing. The double effect of leakage and aliasing will result in the measurement error of the final MTF. Based on the sampling theory, the article quantitatively analyzes the influence of the truncation interval and the sampling interval of the linear expansion function on the MTF at the Nyquist frequency. According to different application and error requirements, the reasonable sampling interval and cutoff interval requirements are given, and the application of fast Fourier transform to edge detection of optical remote sensing camera MTF is regulated.