An ‘electro-forming’ process was generally needed to activate the resistive switching (RS) behavior of Cu/SixNy/Pt ReRAM device. We found the initial forming process would result in a very low RLRS value by using conventional voltage or current sweeping methods, which corresponded to high Reset voltage/current (>2V/10mA) when switching the device back to off-state. By using low constant voltage stress to perform the forming process, the voltage/current of Reset process could be significantly reduced to as small as 0.3V/1μA. After that, excellent RS characteristics of the device were achieved, such as low power, high resistance ratio and multilevel storage, etc.