Abstract: At present, there are many studies on the calculation model of equivalent ice thickness of overhead line under uniform ice cover, but there is a lack of research on OPGW ground ice covering with large cross-section and large unit length weight, especially the applicability of the equivalent ice thickness calculation model under microterrain. In this paper, the three-tower and two-gear OPGW ground wire model under three typical terrains (hillside, mountain top and pass) is established by finite element software, and the error analysis of the equivalent ice thickness model of traditional transmission lines is carried out by combining the equivalent ice thickness model considering the deflection angle of the insulator string, and the results show that the traditional ice thickness calculation error is large when the equivalent ice thickness is small. However, with the increase of the average equivalent ice thickness, the ice thickness calculation error decreases significantly. Based on the above analysis results and the function relationship between the average equivalent ice thickness and the axial tensile force and inclination angle of the insulator string, an ice thickness error optimization calculation method is proposed, and the relative error of the improved ice thickness can be controlled within 10%.