In order to solve the problem that it is difficult to control the deflection in high liquid limit soil subgrade filling, according to the stiffness compensation theory and deflection equivalent principle, taking the deflection as the control objective, the deflection control method is proposed. In this method, the resilient modulus of lower embankment, the resilient modulus of each layer top surface in subgrade and the filling thickness were taken as the calculation parameters. The material modulus required for fillers in each layer was obtained by theoretical calculation, and the appropriate filler was selected according to laboratory test results. The filling scheme of subgrade deflection control can be determined, and it can be dynamically adjusted according to subgrade construction effect. Taking Hainan National Highway G360 as case history, the test road was paved according to the proposed method, and the field test was carried out. The results show that the subgrade top deflection meets the acceptance requirements and the discrepancy is marginal. This method can effectively control the subgrade deflection, and guide the construction and quality control of high liquid limit soil subgrade.