Internet voting protocol is the core of the Internet voting systems. People are focusing on the implementation of coercion-resistant. A coercion-resistant protocol achieves not only receipt-free but also defense against randomization, forced-abstention, and simulation. In this paper, we present an Internet voting protocol that achieves coercion-resistant with few physical assumptions based on designated verifier Proof and proof of knowledge that two ciphertexts are encryption of the same plaintext. In the last we prove that the protocol is invariableness, receipt-free and coercion-resistant.