This paper introduces a new-type of antigravity mixing method, which was applied in the biogas production process, using organic wastewater fermentation. It was found that the digesters with two designs, a high-position, centralized pressure outlet and a high-position, dispersed pressure outlets, both lead to an increase in biogas production rates by 89% and 125%, respectively. The biogas production peak appeared 1 day and 7 days earlier, and the COD removal rates were raised by 27% and 42%, respectively. The results indicated that the optimized flow field had a significant impact. This work also explains the mechanism of flow field optimization using computational fluid dynamics (CFD) software for the simulation of the flow field form in the hydraulic mixing.