Cross-chain exchange swaps assets among different blockchains, which facilitates cooperation among blockchains. A cross-chain exchange contains several transactions from different blockchains. It requires to synchronize asset transfers in those associated blockchains to avoid partial transfers. Current cross-chain methods are divided into two main types. One locks the assets first and transfers the frozen asset to receivers later. The second one is the two-phase or three-phase transaction commit protocol. Those methods require at least two steps, which makes those blockchains coherent to synchronize at different time(steps). Serialization is required as the second step has to wait for the completion of the first step, and even some steps in the same stage are required to be serialized. Meanwhile, their implements are either by smart contracts or special blockchain structures/roles. Smart contract based methods require to pre-deploy a smart contract and cannot change dynamically. Special structure or role-based methods force associated blockchains to have those special requirements. In this paper, we propose a new cross-chain exchange model based on the dependence of associated transactions, which is expressed inside a transaction and can change when sending transactions. It saves the step to lock the asset or perform a pre-commit and has no special requirements for blockchains or pre-deployment of smart contracts. The simulation results show the proposed model exchanges asset effectively among different blockchains.