Abstract The dynamic effect of capillary pressure in oil-water two-phase percolation flow in low permeability reservoirs was investigated by experiment and numerical simulation. An experimental apparatus was constructed to measure the relationship between the dynamic capillary pressure and water saturation change rate, and the dynamic capillary coefficient of low-permeability cores was calculated. A one-dimensional mathematical percolation model was established to analyze the effect of dynamic capillary pressure on waterflooding process. The dynamic capillary pressure effect is too significant to be neglected. The relationship between the dynamic capillary pressure and the change rate of wetting phase saturation is almost linear. The lower the rock permeability is, the greater the dynamic capillary coefficient and threshold pressure gradient are. One of the reasons for non-Darcy two-phase percolation flow is the dynamic capillary pressure effect. The dynamic capillary pressure in low permeability reservoirs has a significant influence on development indices such as the velocity of displacement front, water breakthrough time, pressure distribution, oil production rate, and recovery factor.