Recently, the development of phase change memory (PCM) motivates new hybrid memory architectures that consist of PCM and DRAM. An important issue in such hybrid memory architectures is how to manage the pages resisting in heterogeneous memories. For example, when a requested page is missing in the hybrid memory and the memory has no free spaces, what pages in which type of memory (PCM or DRAM) should be replaced? This problem is much different from traditional buffer replacement management, where they do not consider the special properties of different types of memories. In particular, differing from DRAM, PCM is non-volatile but it has lower access speeds than DRAM. Further, PCM has a limited write endurance which implies that it cannot be written endlessly. Therefore, we have to design a new page replacement algorithm that can not only maintain a high hit ratio as traditional algorithms do but also can avoid frequent writes to PCM. In this paper, aiming to provide a new solution to the page replacement problem in PCM/DRAM-based hybrid memories, we propose a new algorithm called MHR-LRU (Maintain-hit-ratio LRU). The objective of our algorithm is to reduce PCM writes while maintaining a high hit ratio. Specially, it keeps recently updated pages in DRAM and performs page migrations between PCM and DRAM. The migrations take into account both page access patterns and the influences of page faults. We conduct trace-driven experiments and compared our proposal with some existing algorithms including LRU, LRU-WPAM, and CLOCK-DWF. The results show that our proposal is able to efficiently reduce PCM writes without degrading the hit ratio. Thus, our study offers a better solution for the page replacement issue in PCM/DRAM-based hybrid memory systems than previous approaches.