The suspension bridge scheme was adopted in the Chong qing Egongyan Bridge. East anchorage used as one of anchors was a tunnel anchor buried in siltstone and sand-mudstone layers of rock mass, and the deformation states of the anchorage and surrounding rock would influence the stability and security of the bridge directly. The deformation data of the anchorage and surrounding rock under the action of 4.6 times design load were obtained by a scale 1∶12.5 structure model test in situ. Through analysing the tested load*.deformation curve it is demonstrated that t he deformation of the anchoruge and surrounding rock is small, being within their elastic stage. Based on the test data, a grey-forcasting model GM(1,1) was established, by which the rock utmost limit bearing capacity is forecasted to be 6.09～6.15 times as much as its design load, the tunnel anchorage is in safe state, and has enough safety storage.