In this paper, the main beam, which is one of the critical components of Horizontal Directional Drilling (HDD) GD2800-L, is selected as a subject investigated. The geometric model of HDD is firstly established, its static and buckling analysis are also taken to get the stress and deflection distribution, buckling mode and critical load by the ANSYS. Acquired results show that the working condition of main beam is mainly decided by HDD penetrating angle and the most dangerous working condition is its working at maximum penetrating angle. In order to decrease weight of main beam, its optimization design has been further completed, and 13 percent of main beam weight is reduced, but stress and deflection distribution increase slightly within bounds. The methods can greatly improve design efficiency and reduce steel plate consumption and product manufacturing cost.