Temperature-tuned and domain-tuned signal-resonated optical parametric oscillator based on multi-grating periodically poled Mgo-doped lithium niobate and pumped by an acousto-optically (A-O) Q-switched 1064 nm NdYVO4 laser was studied experimentally. The signal wave of 1450～1839 nm could be obtained with poled periods varying from 29.0～31.5 μm and temperature varying from 30～180℃, covering the S+C+L+U wave bands of optical fiber communications, and the range of corresponding idler-wave was 2909～3990 nm. When the pump power was 830 mW, the maximal output power of signal wave was 139.7 mW, the conversion efficiency was 16.8%, and the lowest lasing threshold was 88 mW. The tunable light source has reached the practical power level of optical communications system.