Abstract: High-speed rail grinding test-beds are an important tool to study the mechanism of high-speed grinding. The main difference between the test condition and the real grinding process is that the radii of curvature along the longitudinal direction are different between the test-bed and real grinding. The rail has a finite radius on the test-bed but is straight in reality. This may lead to differences between the tangential grinding force measured on the test-bed and what happens in real grinding. In this paper, a method is established based on the theory of grinding to calculate the tangential grinding force taking the radius of curvature of the ground rail into consideration. The calculated tangential grinding force agrees well with experimental measured grinding force on the test-bed. A correction factor k is proposed based on this method to eliminate the error of the tangential grinding force measured on the test-bed. The effects of normal loading and the radius of the rail on the correction factor k are studied using the established method.