Abstract： The Poincaré group is adapted as the gravitational gauge group. The equation of gravitational field in the Reimann-Cartan space-time with a Lagrangian containing linear and quadratic terms of strengths is investigated. For static and spherically symmetric field the vacuum solution in the macroscopic limit is shown to correspond to Schwar-zchild solution. Therefore this is in agreement with the experiments for general relativity. But in the microscopic limit, the field equation may predict a new type of short-range interaction.The spin 1/2 particle, Dirac particle, is taken as a probing particle. Its motion in the vacuum static and spherically symmetric gravitation field is explored. As a result, it is shown that the equation of motion of the Dirac particle only depends upon the Reimannian part of affine connection and has the same form as the corresponding equation of general relativity.