[Purposes] This work aims to improve the stiffness of soft ground and determine the materials and thickness for treatment scientifically. [Methods] Based on the ground treatment project of the freight yard of Baise East Railway Station in Guangxi, a stiffness enhancement method aiming at the equivalent resilient modulus at the top surface was proposed based on the theory of elastic half?space and elastic double?layer system. The stiffness enhancement method evaluated and optimized the original foundation treatment scheme, whose validity and rationality was verified by the in?situ test results of resilient modulus. Subsequently, the economic efficiency of the optimized and the original scheme was compared and analyzed. [Findings] The results showed that the resilient modulus at the top surface of the foundation in the original scheme could not meet the design requirements. Changing the thickness of 1.0 m lime?improved soil (lime content 30%) to 0.8 m and laying 0.2 m thick graded crushed stone above， the equivalent resilient modulus at the top surface of the foundation can increase from 44.0 MPa to 78.0 MPa. The average value of resilient modulus measured on the top surface of the foundation was about 79.0 MPa. The optimized scheme has significant advantages in terms of reducing engineering costs. [Conclusions] This study can provide foundation treatment and pavement structure design references.