We demonstrate a compact, high efficiency and widely tunable intracavity singly resonant optical parametric oscillator (IC-OPO) based on multichannel periodically poled lithium niobate (PPLN). The IC-OPO is composed of 808 nm pump laser diode (LD), Nd:YVO4 laser and linear OPO. The continuous-wave (CW) mid-infrared (MIR) output laser is tunable from 2.25 to 4.79 μm. The maximum output power exceeds 1.08 W at 3.189 μm at 9.1 W LD pump power and the conversion efficiency is 11.88%. We also build up a prototype with volume of 145 × 85 × 42.5 mm3 and its total weight is less than 2 kg. The measured power stability is 1.3% Root Meat Square (RMS) for a 3 h duration under simulated high temperature conditions of 40 °C. RMS is 2.6% for a 4 h duration when simulated temperature is - 40 °C.