In order to increase the output of single well and study the controlling factors of waterflooding in ultra-low permeability oilfields, the stable and high production of oilfields can be realized. Based on the collation and analysis of dynamic data, production test and production test data, the square inverse nine-point method is used to analyze the water injection effect and its controlling factors in the subgroup well pattern of Chang 4+52 reservoir in Madigou oil area of Hengshan oilfield. The results show that the effective effect of oil well can be divided into three types: obvious effective, medium effective and weak effective, accounting for 48.28%, 41.38% and 10.34% respectively. The main controlling factors are sedimentary microfacies, permeability and well spacing. Distributary channel sand body is developed. The thicker the sand body is and the better the connectivity is, the easier the oil well is. The better the injection-production effectiveness of the oil well is, the better the permeability is, and the higher the permeability is, the easier it is for the oil well to be effective. Injection-production well spacing is distributed from 150 m to 300 m, indicating that well spacing is not the only factor affecting injection-production effectiveness, and the selection of well spacing is closely related to sand body thickness, connectivity and reservoir physical properties in the study area.