The invention discloses a method and a device for time synchronization of serial messages in a master-slave system. The system comprises a host and at least one slave. A high-speed serial bus is usedfor communication between the master and the slave. The host serves as a clock source, and the slaves serve as time-served devices. The time tick process comprises the following steps that: a host issues a time tick message, wherein the sent time tick message comprises an accurate timestamp corresponding to a sending starting moment; the slave receives the time tick message issued by the host andrecords the time of receiving the message; acquiring message sending transmission delay; and the slave calculates the accurate time difference between the local clock source and the host clock sourceaccording to the timestamp in the host time tick message, the message sending transmission delay and the crystal oscillator deviation so as to calculate the local accurate time. According to the system, one high-speed serial communication bus is used, accurate message time synchronization and high-speed data communication are completed, the wiring complexity and cost are reduced, and high practical value is achieved.