The converter station acts as the core component of a direct current (DC) transmission project. Effective control over the total ground electric field within the DC yard of the station is critical for ensuring environmental protection and advancing the sustainable development of DC transmission projects. Notably, the ground total electric field in ultra-high voltage direct current (UHVDC) converter stations directly affects the health of on-site operators, making its proper management an essential requirement. At present, China is actively advancing the planning, design, and construction of the “Tibet Power Transmission” ultra-high voltage direct current (UHVDC) transmission project. However, there remains a lack of measurement data on the total electric field in UHVDC converter stations at high altitudes. This paper conducts testing and analysis on the ground total electric field in the DC yard of the Hainan Converter Station located at an altitude of 3,000 m. The results show that: in most areas of the DC yard at Qingnan Station, the maximum ground total electric field (absolute value) is below the design limit of 30 kV/m; the corona discharge phenomenon is insignificant or absent in high-end tube busbars, station outgoing lines, and smoothing reactors within the DC yard, with the ground total electric field primarily or entirely consisting of the nominal electric field; additionally, grounded metal conductors (including support columns and fences) in the DC yard exhibit significant suppression effects on the ground total electric field. The findings of this study can provide reference for the design of tube busbar selection in DC yards of converter stations at higher altitudes.