A processing node, a computer system, and a transaction conflict detection method, where the processing node includes a processor and a transactional cache. When obtaining a first operation instruction in a transaction for accessing shared data, the processor accesses the transactional cache for caching shared data of a transaction processed by the processing node. If the transactional cache determines that the first operation instruction fails to hit a cache line in the transactional cache, the transactional cache sends a first destination address in the operation instruction to a transactional cache in another processing node. After receiving status information of a cache line hit by the first destination address from the other processing node, the transactional cache determines, based on the received status information, whether the first operation instruction conflicts with a second operation instruction executed by the other processing node.