Resistive switching behaviors of amorphous MoO(x )thin films prepared by magnetron sputtering at room temperature have been investigated. Ag/MoOx/ITO device shows a bipolar resistive switching without electroforming process. A very low set voltage of about 0.4 V and a reduced set power below 50 mu W can be achieved based on the amorphous MoOx thin films. Schottky emission and oxygen vacancies in the amorphous film can be used to understand the physical mechanism for the observed resistive switching behaviors. Moreover, analog resistive switching is demonstrated in the device. The synaptic plasticity of the device can be controlled by the interval, and amplitude of input voltage pulse stimulation. This study provides us opportunity to investigate the potential applications in neuromorphic computing based on our Ag/MoOx/ITO memristors.