Safety protection method of CBTC (Communication Based Train Control) system during crossing control area

The invention provides a safety protection method of a CBTC system during crossing a control area, which comprises the steps: S1: when the train enters the boundary areas of a first and a second ground ATP systems, the first and the second ground ATP systems mutually transmit the information of access roads R1 and R2 of respective control areas; S2: the first ATP calculates first moving authorization information according to the information of the access roads R1 and R2 and transmits the information to a vehicle-mounted ATP; S3: when the train passes through the boundary point of the boundary area and enters the control area of the second ATP, the vehicle-mounted ATP transmits chain-scission request information to the first ground ATP system and transmits chain-building request information to the second ground ATP system; and S4: the second ground ATP system responses the chain-building request information, calculates second moving authorization information according to the information of the access road R2 and transmits the second moving authorization information to the vehicle-mounted ATP. The invention can ensure that the arrangement of the access road R2 in the boundary point can not be limited; the vehicle-missing phenomenon can not appear when the train breaks down in OB zones; and the cost of the system can be simultaneously reduced.