Three 1 000 kV circuit breakers are added to the expansion project of Jingmen UHV substation. Hybrid gas insulated switchgear (HGIS) is applied that the arrangement of 1 000 kV main wiring was changed from double breaker transition connection to 3/2 circuit breaker connection. With the construction characteristics of Jingmen substation expansion project concerned, “2+1” and “3+0” layout mode of 1 000kV HGIS are analyzed. The uneven settlement problem of HGIS foundation under the “3+0” mode is studied. Then, the uneven settlements in early and late stage are both calculated. Finally, it is suggest that the compensation units of anti-sedimentation telescopic corrugated pipe should be added in order to ensure the safe operation of the equipment.