Two optimization strategies based on Bloom Filter are proposed for P2P security. In order to protect the privacy of trust information in P2P systems, BFManager using BloomFilter is employed to manager trust information, and builds a structure called trust bucket to store trust value and divides peers with different trust value into different trust buckets. The other is called as BFChecker to optimize current file checking, which integrates all hash value of file pieces into a BloomFilter structure. The experimental results demonstrate their effectiveness and efficiency of both strategies.