Pile-anchor support in foundation pit in expansive soil regions puts forward higher requirements for anchors. By example of an expansive soil foundation pit in the eastern suburbs of Chengdu，comparative on-field tests on ultimate pullout force and creep-relaxation characteristics are carried out between under-reamed compression anchors and normal tension anchors to study the feasibility of pile-anchor support in the foundation pit. Test results show that under-reamed compression anchors present high bearing capacity and good deformation control，and creep and stress relaxation characteristics are better than normal tension anchors. Based on field test results，the anchor-pile support scheme by combining under-reamed compression anchors and support piles is adopted through scheme comparison to conduct the application study. The pullout tests of the anchors are conducted and anchor stress state is monitored in the application study. The horizontal displacements of foundation pit and the settlements of the surrounding buildings are monitored as well. The results show that the under-reamed compression anchor has good applicability in foundation pit engineering in Chengdu expansive soil regions. The research results can provide reference for the design of foundation pit support in similar project.