We investigate the impact of N+-N,P+-P and PN junction depth on the single-event transient (SET) pulse width in nano technology through TCAD simulations. The variations of voltage or temperature are also considered. Simulation results indicate that N+-N junction plays the most important role in influencing the SET pulse width. Meanwhile, we also investigate the impact of voltage and temperature on junction depth. Simulation results indicate that the voltage can significantly affect N+-N and P+-P junction while the temperature can significantly affect PN junction.