Inverse synthetic aperture radar (ISAR) imaging plays an important role in modern radar systems. It is a powerful tool to surveil the air and space targets under all-weather and day-and-night conditions. With increasing demands for space surveillance and target recognition, real-time ISAR imaging is of great urgency. Based on field programmable gate arrays and digital signal processors, a new design of real-time processing of ISAR imaging is presented in this paper. First, a thorough description of the imaging algorithm is presented. The algorithm includes pulse compression, envelope alignment, phase adjustment, and cross range focusing. For the pulse compression, two different methods are adopted to process the "Dechirp" data and the directly sampled wideband data, respectively. Second, a hardware design of real-time imaging processing is given. Each step of the algorithm is mapped onto the hardware, and the computing resources and latency are analyzed. Finally, the realization is verified by both the simulated and measured data, and the quality of imaging result is evaluated qualitatively.