A system and a corresponding method for multi-core synchronous debugging of a multi-core platform including a plurality of cores are provided. The method includes the following steps. Transmit a core debugging instruction to one of the cores selected by a system debugging instruction or store a group setting included in the system debugging instruction according to the type of the system debugging instruction. Control every core in a group to start executing program instructions simultaneously according to another system debugging instruction. The group is a subset of the cores and the group setting indicates which ones of the cores are included in the group. Use a handshaking mechanism to control all cores of the group to enter a debug mode simultaneously when a debug event happens in any core of the group.