Due to the reduction of transistor size, modern circuits are becoming more sensitive to soft errors. The development of new techniques and algorithms targeting soft error detection are important as they allow designers to evaluate the weaknesses of the circuits at an early stage of the design. The project presents an optimized implementation of soft error detection simulator targeting combinational circuits. The developed simulator uses advanced switch level models allowing the injection of soft errors caused by single event-transient pulses with magnitudes lesser than the logic threshold. The ISCAS'85 benchmark circuits are used for the simulations. The transients can be injected at drain, gate, or inputs of logic gate. This gives clear indication of the importance of transient injection location on the fault coverage. Furthermore, an algorithm is designed and implemented in this work to increase the performance of the simulator. This optimized version of the simulator achieved an average speed-up of 310 compared to the non-algorithm based version of the simulator.