Aiming at the existing characters and deficiencies of the drilling experiment platform, a new kind of multifunctional drilling comprehensive experiment platform was designed. First of all,a new way to balance the drill rig load based on its design was put forward. Then by the internal and external balance methods,the results were calculated and compared,and the different effects on the experiment platform performance were obtained. Finally,according to the design characteristics of the drilling comprehensive experimental platform that could drill obliquely,the load mechanical property of the pit shaft was analyzed at different balance conditions,and the key technical parameters of the experiment platform design was got.The results show that the portal frame or pit shaft can support the drill pipe axial load in different balance ways. In essence,the load is transferred or transformed between the portal frame,pit shaft,track and foundation. Considering from the point of safety,using the scheme of the portal frame under load（ external balance mechanical system） is superior to the internal balance scheme of the pit shaft. The research method and conclusions have reference significance for optimal design,failure analysis and safety evaluation.