The present disclosure discloses a time synchronization method. In the method, a first node sends a first time packet at a first time over a first working wavelength; a second node receives the first time packet at a second time. The first node sends a second time packet at a third time over a second working wavelength. The second node receives the second time packet at a fourth time; calculates an absolute time deviation between the second node and the first node according to the first time, the second time, the third time, the fourth time, a first signal transmission rate corresponding to the first working wavelength, and a second signal transmission rate corresponding to the second working wavelength, and synchronizes the local time between the second node and the first node. Further, a time synchronization system and a node device are disclosed.