In order to provide a TDI function for CMOS area image sensors,the working principles of TDICCDs are researched and a TDI algorithm based on the digital domain is proposed,then,how to realize the algorithm by a FPGA is discussed. The algorithm can realize time delay integration on CMOS sensors without changing its device structure.The TDI algorithm for CMOS area image sensors in a digital domain is deduced through an example method.After optimization,the algorithm with optimized structure can save (m-1)(m-2)/2 memory space of image lines. Finally,on the basis of a remote sensing camera,the dependence of pixel resolution and row transfer time on frame rate is discussed and the frame rate requirements under the Ground Sample Distances(GSDs) and TDI stages are calculated by the numerical example method.Experiment results show that the 1 280×1 024 CMOS sensor with a frame rate more than 648 frame/s can meet the requirements of integration imaging for 1 m GSD of 96 TDI stages in an orbital altitude of 600 km.