The metro system plays a crucial role in urban transportation nowadays. However, its operational efficiency often suffers due to various failures, especially train failures. In such cases, a train rescue operation becomes necessary to restore normal operations. This paper introduces five rescue stages and common rescue routes for train rescue operations. Moreover, it presents a mixed-integer non-linear programming model to address the train rescheduling problem, specifically focusing on the pushing-forward rescue strategy. The proposed model aims to achieve multiple objectives, including minimizing timetable deviations, headway variations, the number of canceled stops, and the required rolling stocks. To account for operational constraints, the model incorporates arrival and departure time constraints, headway constraints, rolling stock circulation constraints, and rescue operation constraints. The non-linear problem is then transformed into a linear problem that can be efficiently solved using the CPLEX optimization solver. To validate the model's effectiveness, extensive numerical experiments are conducted using real-world data from Beijing Subway Line 7. The computational results demonstrate that the rescheduling strategies proposed in this paper effectively address the train rescheduling problem under train rescue operations.