The development of blockchain technology is influenced by user diversity and application scenarios, resulting in limitations on the applicability of assets. Although cloud computing is renowned for facilitating cross-chain token transfers, it lacks a robust trust mechanism. Existing cross-chain transaction solutions are typically confined to interactions between two blockchains or within established networks. Hence, constructing a trustless cross-chain transaction protocol remains a significant challenge. This study proposes a trustless third-party cross-chain asset trading solution, Vchain, based on a Blockchain of Blockchains architecture and driven by a relay chain. This solution supports various blockchain ecosystem accounts and leverages cloud computing to integrate external data sources and API calls to obtain the latest token exchange rates, ensuring transaction accuracy and real-time performance. Simulation results demonstrate that Vchain’s cross-chain transaction costs are \(69.25\%\) lower than those of existing models. The research indicates that Vchain offers significant advantages in enhancing transaction efficiency and reducing costs, effectively addressing current challenges in cross-chain transactions.