We report herein a continuous-wave mid-infrared intra-cavity singly resonant optical parametric oscillator (ICSRO) which is the first example of ICSRO that utilize in-band pumped Nd-doped vanadate laser as pump source. A 1064 nm Nd:YVO₄ laser in-band pumped by 880 nm LD and a periodically poled lithium niobate (PPLN) crystal are employed as the parent pump laser and the nonlinear medium, respectively. The idler output wavelength tuning range is 3.66-4.22 µm. A maximum output power of 1.54 W at 3.66 µm is obtained at absorbed pump power of 21.9 W, with corresponding optical efficiency being 7.0%. The control experiment of ICSRO under 808 nm traditional pumping is also carried out. The results show that in-band pumped ICSRO has better performance in terms of threshold, power scaling, efficiency and power stability than ICSRO traditionally pumped at 808 nm.