This study investigates the secure control problem of Markov jump cyber-physical systems (CPS) under mode-dependent denial of service (DoS) attacks. A novel mode-dependent event-triggering strategy is adopted to reduce the network resource consumptions. In particular, the DoS attacks are supposed to be mode-dependent for more practical applications. The Lyapunov-Krasovskii functional method is utilized to establish the sufficient conditions such that the resulting closed-loop system can be uniformly ultimately bounded under DoS attacks. Furthermore, the desired secure controller can be designed in terms of matrix techniques. Finally, an illustrative example is presented to demonstrate the effectiveness of the theoretical method.