The invention relates to a bus communication method for a time synchronization device and a bus communication device for the time synchronization device. The method comprises the following steps that A, a master node unit sends a slave node type inquiry frame to slave node units; B, each slave node unit sends a slave node type replying frame; C, if the master node unit receives the slave node type replying frames, a slave node address list is updated, and otherwise, the step F is executed; D, the master node unit sends a slave node state inquiry frame, and each slave node unit sends a slave node state replying frame; E, if the master node unit receives the slave node state replying frames, a slave node state list is updated, and otherwise, the step F is executed; F, if a user has an instruction, the instruction of the user is executed, and otherwise, the step G is executed; and G, the steps are executed on a next slave node insertion slot. The master node unit continuously inquires the slave node unit type and the work state of all slave node units, and the on-line and work state of the slave node units can be mastered in real time.