A control method and a time aware bridge device for a seamless Precision Time Protocol (PTP) are provided. The control method includes: utilizing the time aware bridge device to pre-configure a first control signal source as a master control signal source, and pre-configure a second control signal source as a backup control signal source; utilizing the time aware bridge device to determine whether one or more packets from the master control signal source conform to at least one predetermined rule to generate a determination result; and selectively configuring the second control signal source as the master control signal source according to the determination result.