In this paper, we target on energy-efficient design of soft real-time and reliable applications on uniprocessor embedded systems. We consider soft real-time tasks with stochastic execution times with given distribution. Instead of guaranteeing hard real-time constraint, the application may be finished after their deadlines with a certain probability. We utilize Dynamic Voltage and Frequency Scaling (DVFS) to save energy, and also take into account of the impact of DVFS on reliability. Our objective is to minimize the expected energy consumption of the system subject to statistical reliability and deadline constraints. Due to the huge complexity of solving the problem exactly, we develop a fast bi-search approach based on dynamic programming, which can find the near-optimal solution with energy cost at most (1+beta) times of the optimal energy and has polynomial time complexity. Extensive experiments and a real-life application were conducted to evaluate the efficiency of the proposed techniques.