Making friends with some common attributes is one of the most popular applications in the mobile social networking (MSN). However, how to preserve the users' privacy while matchmaking has been considered as the key security issue for such applications. In this paper, based on the definitions of the privacy level, a new privacy preserving matchmaking system and protocol for MSN is proposed, which can help users to find their friends without leaking their privacy information. A user (called initiator) can find the best match among the candidates, and only exchange attributes intersection set with the best matched, while other users only know the size of the attributes intersection set mutually. The analyzing and simulation results show that our protocol is efficient with the ability to resist the semi-honest and malicious attacks while providing higher matchmaking efficiency.