In this study, resistive switching behaviors of Ag/SiN/p -Si device were investigated by adjusting nitrogen concentration and layer thickness. The device with a nitrogen concentration of 50% and a thickness of 10 nm has a typical bipolar resistive switching behavior with a low forming voltage (~ 4 V), a high on/off ratio (~ 102), an excellent endurance (>102) and a long retention time (>105 s). According to I–V characteristics analyses, electric transports in both a high resistance state and a low resistance state are dominated by hot electron emission which is caused by the electron trapping and detrapping through immovable nitrogen-related traps. The temperature dependence of a resistive switching behavior not only illustrates the existence and importance of the traps, but also discovers a new phenomenon of the transition about the polar of a resistive switching method. Surely, more efforts need to be made for deeper understanding of the carrier transport in SiN thin films.