Reconfigurable computing system has the flexibility of traditional processor and the speed of ASIC approximately. Dynamic partial reconfigurable system realizes the computing and reconfiguration at the same time, in which an efficient free resource management scheme is very important to achieve high performance. I}his paper introduced an effident algorithm to find a series of maximal free rectangles (MFR) based on one-way stack. The algorithm uses different M value in and out of oncway stack to find all maximal free rectangles. We used simulation experiments to simulate the algorithm, and the results show that the this algorithm improves the performance of searching complete free resources.