Abstract: For passive radar, the computation cost of traditional 2-dimentional coherent integration (ambiguity function) is high, which makes it hard to perform in real-time processing. And range migration may occur during the integration time, leading to a Signal-to-Noise ratio (SNR) decrease. The migration may cause a detection ability loss. A migration compensation algorithm is proposed with keystone transform based on a real-time integration method in this article to realize real-time processing of 2-dimational integration. The real-time integration includes: 1-dimentional signal is divided into segments, match filtering is applied to each segment, and FFT is applied across segments. An improved segment method is introduced for application demand. Based on this method, an effective method to rectify range migration is proposed using keystone transform in this article, enhancing the detection ability of weak targets. The algorithm can improve computation efficiency with less energy loss, and is easier to perform in real-time then other algorithms. So its a real-time and efficient target detection method. In this article the real-time processing ability of integration and migration compensation is analyzed. Experiments based on simulated signal and real-life signal show that the algorithm can realize real-time processing with effective processing gain.