Trade honestly is very important since fraud has been on rise recently and it prevents people from partici-paring in online electronic markets. Since simple feedback mechanism cannot promote honest trade, this paper proposes a new incentive mechanism, named Register Deposit and Trade Security Deposit Mechanism, which helps to manage online markets. It not only rebuilds the aggregation of trust signal--reputation index but also uses trade security deposit to avoid participant fraud and force people to trade honestly. By the behavior analysis between buyers and sellers with the Register Deposit and Trade Security Deposit Mechanism, we proved that the strategy of honest trade is not only the Nash Equilibrium in single-stage game, but also the Sub-game Perfect Nash Equilibrium in repeated game. Finally, we make simulation experiment on the mechanism with random trade data from eBay online market, and verify the validity of the mechanism