A heartbeat-based data synchronization method is disclosed. The method is applied to a distributed storage system, and at least one data block group is stored in the distributed storage system. The distributed storage system includes multiple storage devices, one device in the multiple storage devices is a primary device for storing the data block group, and other devices are secondary devices for storing the data block group. The primary device performs the method. The primary device obtains access status information of the data block group, determines a heartbeat time of the data block group according to the access status information of the data block group, and sends a data synchronization instruction to the secondary device according to the heartbeat time of the data block group, where the data synchronization instruction is used to instruct the secondary device to synchronize data.