User authentication scheme for sensor networks is proposed. In proposed scheme, we employ polynomial share and the hash value with a secret key as the basic means of constructing node authentication procedure in order to avoids the need for public key cryptography and reduce shortage overhead. The proposed scheme not only can achieve authentication mutually between communication two parts and prevent malicious nodes from joining sensor networks, but also can easily add new sensor nodes to sensor networks. Furthermore, The proposed scheme can simply and efficient establish share key between two nodes, therefore it can perform secure communications with them.