<p>Accurate measurement of soil stress is essential for understanding the mechanical behavior of soil and ensuring the safety and stability of geotechnical structures. Earth pressure cells (EPCs) are extensively employed to measure normal stress in soil and soil-structure contact stress. However, discrepancies between EPCs and surrounding soils in terms of physical and mechanical properties lead to stress concentration and redistribution, resulting in measurement errors. This study proposes a novel selection criterion for EPCs based on the diameter-to-height ratio (D/H) and elastic modulus, validated through an independent test system. Through three-dimensional numerical simulations and laboratory tests, we systematically analyze how the diameter-to-height ratio (D/H) and the elastic modulus of EPCs influence the stability and reliability of measured stress values. The results demonstrate that increasing the D/H ratio and the elastic modulus of EPCs significantly enhances the accuracy of stress measurements. Based on these findings, we propose optimized selection criteria for EPCs to guide their application in geotechnical engineering. The study concludes that EPCs with a larger D/H ratio and higher elastic modulus yield more reliable measurements, offering a significant advancement in optimizing EPC design for geotechnical engineering, particularly in tunnel construction.</p>