The output characteristics and coexistent stimulated Raman scattering of a multi-wavelength tunable optical parametric oscillator (OPO), which is pumped by an all-solid-state NdYVO4 laser with the 1064 nm wavelength, are investigated by quasi-phase-matching period tuning technology. An experiment using the continuous wave (CW) operation mode, single resonant optical parametric oscillator and external cavity structure is carried out based on the PPMgLN crystal. Experimental results indicate that the widely tunable near-infrared spectrum from 1435.9 to 1670.2 nm and mid-infrared spectrum from 4185.0 to 2970.4 nm are obtained. The maximum total signal and idler output power at 30.5 μm poling period is 4.29 W when pump power is 11.79 W, which corresponds to an optical-optical efficiency of 36.4%. Coexistent CW OPO and stimulated Raman scattering (SRS) are demonstrated with 28.5, 30.0 and 30.5 μm poling periods. With the loss of SRS increasing, 1.98 W of the maximum idler output power at 3451 nm is obtained, corresponding to an optical-optical efficiency of 16.8%. An extra-cavity, widely tunable, high power and continuous wave singly resonant CW-PPMgLN-OPO at the signal and idler wavelength is realized, and the coexistent Raman scattering has an important effect on the output of the idler.