This paper proposes a new relaxation-based circuit simulation algorithm that is more flexible, robust and efficient than traditional methods such as Waveform Relaxation (WR) and Iterated Timing Analysis (ITA). The new method employs a brand new strategy, which concentrates on the subcircuit scheduling, to undertake the simulation process. Simulated by this new method, subcircuits can be scheduled for calculating in ITA or WR fashions according to their dynamical coupling situations. We have proposed a recursive pseudo code for this new method. A circuit simulation program based on the pseudo code has been implemented, and various circuits have been tested to justify its performance.