In this paper, the influence factors of development effect of heavy oil reservoir by water flooding are analyzed and studied by numerical simulation technology. The results show that: (1)with the increase of crude oil viscosity, reservoir recovery decreases gradually and development effect becomes worse; (2) for heavy oil reservoirs with different viscosities, recovery increases at first and then decreases slowly with the increase of permeability; (3)water injection development is carried out under different formation pressure maintaining horizontal conditions, the results show that the maximum development efficiency of reservoir recovery is achieved under saturated pressure conditions. The results show that there are optimal injection velocities for different permeability reservoirs, such as 0.06 PV/a for 100 md reservoir, 0.10 PV/a for 500 md reservoir and 0.04 PV/a for 1000 md reservoir.