Abstract: In order to direct the application of the prestressing anchorage cable in loessland,in-situ test and mathematical analysis are took as research means and the anchorage cable's deformation are measured on tensile test through the resistance foil gauge.The strain curve is derived in diffirent state of tension in loessland.Using the formula of Philips and uniform binding stress to analyze the test data,two formula of calculating anchorage force have been deduced.It is pointed out that the theory of Philips can show more veritably the character of anchorage force in loessland.