A surface-emitted ring-cavity terahertz (THz) wave parametric oscillator is constructed based on the 1% molar fraction of MgO-doped near-stoichiometric lithium niobite crystal, whose output THz frequency tuning range is 0.99-3.84 THz and frequency tuning response time is 600 μs. When the pump pulse energy is 150.30 mJ and the THz frequency is 1.59 THz, the output energy of the THz pulse is the maximum 16.28 μJ and the corresponding energy-conversion efficiency is 1.08×10 -4. Moreover, under the same experimental conditions, the maximum THz wave output energy from this ring-cavity THz wave parametric oscillator is about 2.35 times that obtained from the conventional linear-cavity ones. The THz wave output with high-energy and rapid-tuning is realized.