A control method for supporting dynamic coupling and uncoupling of a train by an on-board signal system, wherein an on-board controller stores on-line coupling status information with security coding and pre-stores off-line configurations while collecting hard-wired input signals from the train in real time and performing corresponding controls, the method comprising steps of: step A, acquiring stored coupling status information during an initialization phase; step B, loading an off-line configuration of a corresponding composition according to the stored coupling status; step C, collecting input signals related to the coupling; step D, determining whether a train coupling status is proper according to the collected signals, then turning to step E if yes and turning to step F if no; step E, determining whether a current coupling status is consistent with the off-line configuration used in the step B, then performing step H if yes and performing step G if no; step F, requesting emergency braking, and reporting an alarming error; step G, requesting emergency braking, re-writing coupling status information with codes after determining that the train is stationary, and then turning to the step A for re-initialization; step H, performing other functions of the signal system; characterized in that: the on-board controller stores on-line coupling status information with security coding and pre-stores three sets of off-line configurations while collecting three sets of hard-wired input signals from the train in real time and performing corresponding controls; in step C, three sets of input signals related to the coupling are collected; and in step D, the determining whether the train coupling status is proper according to the collected signals has a determination logic shown in a table as below, wherein combinations 2, 3, and 5 are proper, and the rest are improper: Combination No. Three Collected Sets of Train Coupling Signals Coupling Status ANS ACS1 ACS2 1 0 0 0 Improper 2 0 0 1 Driver's cab 2 Coupled 3 0 1 0 Driver's cab 1 Coupled 4 0 1 1 Improper 5 1 0 0 Not Coupled 6 1 0 1 Improper 7 1 1 0 Improper 8 1 1 1 Improper step A, acquiring stored coupling status information during an initialization phase; step B, loading an off-line configuration of a corresponding composition according to the stored coupling status; step C, collecting input signals related to the coupling; step D, determining whether a train coupling status is proper according to the collected signals, then turning to step E if yes and turning to step F if no; step E, determining whether a current coupling status is consistent with the off-line configuration used in the step B, then performing step H if yes and performing step G if no; step F, requesting emergency braking, and reporting an alarming error; step G, requesting emergency braking, re-writing coupling status information with codes after determining that the train is stationary, and then turning to the step A for re-initialization; step H, performing other functions of the signal system; characterized in that: the on-board controller stores on-line coupling status information with security coding and pre-stores three sets of off-line configurations while collecting three sets of hard-wired input signals from the train in real time and performing corresponding controls; in step C, three sets of input signals related to the coupling are collected; and in step D, the determining whether the train coupling status is proper according to the collected signals has a determination logic shown in a table as below, wherein combinations 2, 3, and 5 are proper, and the rest are improper: Combination No. Three Collected Sets of Train Coupling Signals Coupling Status ANS ACS1 ACS2 1 0 0 0 Improper 2 0 0 1 Driver's cab 2 Coupled 3 0 1 0 Driver's cab 1 Coupled 4 0 1 1 Improper 5 1 0 0 Not Coupled 6 1 0 1 Improper 7 1 1 0 Improper 8 1 1 1 Improper the on-board controller stores on-line coupling status information with security coding and pre-stores three sets of off-line configurations while collecting three sets of hard-wired input signals from the train in real time and performing corresponding controls; in step C, three sets of input signals related to the coupling are collected; and in step D, the determining whether the train coupling status is proper according to the collected signals has a determination logic shown in a table as below, wherein combinations 2, 3, and 5 are proper, and the rest are improper: Combination No. Three Collected Sets of Train Coupling Signals Coupling Status ANS ACS1 ACS2 1 0 0 0 Improper 2 0 0 1 Driver's cab 2 Coupled 3 0 1 0 Driver's cab 1 Coupled 4 0 1 1 Improper 5 1 0 0 Not Coupled 6 1 0 1 Improper 7 1 1 0 Improper 8 1 1 1 Improper