Abstract: This paper proposes an improved key management scheme based on random key-seeds predistribution for wireless sensor networks (WSNs). According to the key generation method which needs the key-seed and generation factor, we formulate the proper key generation and update methods with different key types. The analysis and simulation of connectivity rates and security show that our scheme can enhance the capability against nodes capture and provide high flexibility. Finally the scheme is implemented on the Lab platform. The analysis indicates the feature of low overhead in communication, computation and storage.