In the rail transit system,the running foundation of the computer control system is required to be highly reliable,available and safe.A redundant system structure of double one out of two with a hot standby applied to the safety computer platform of the train control system is proposed in this paper.Considering the common cause failure,fault diagnosis rate,repair rate and switching success rate,the Markovian approach is adopted for modeling four safety redundant structures,including two out of three,double one out of two,one out of two with a hot standby and double one out of two with a hot standby.The calculation of the failure rate and P F H values is carried out with MATLAB to evaluate the reliability,safety and influencing factors of each structure.The final conclusion is that double one out of two with a hot standby structure can be best in the aspect of both reliability and safety with appropriate DC and β parameters.