Abstract: On the basis of prior trial production of the new type unbrella shaped self expanding anchor, its pull out tests and the comparative tests between the new type and screw anchors, this paper analyses the characteristics of load displacement curves of the new type anchors, divides its self expanding process into three different stages, and discusses its self expanding mechanism. It is found that the new type anchor can automatically expand its psrts into an umbrella shaped structure under the ground when the pull out load is applied, and then it uplift capacity can be remarkably improved. At the end of this paper, proposals are presented for further research.