In this paper, we study a secure multi-party ranking problem: there are n parties, P_1, P_2, ..., P_n. Each party P_i has a secret input m_i \in {1, 2, ...,N}. He wants to get the order of mi in the ascending ranking sequence of the n parties' inputs, while not leaking the value of mi. This problem extends the famous Yao's Millionaires' problem form two paries to n parties and is a multi-party Yao's Millionaires' problem. We propose a protocol for solving the secure multi-party ranking problem, using the encoding scheme and the El Gamal cryptosystem. We also prove the correctness and the security of our solution in the semi-honest model. The solution of secure multi-party ranking problem can make new-style electronic transactions, such as private biding and auction, secret online transaction and so on, become better security.