As　a　result　of　the　limitation　of　testing　environment　area　and　testing　equipment,　the　existing　the　rigid　structure　of　the　feeding　device　or　multistage　hydraulic　cylinder　cantilever　mechanism　can＇t　meet　the　requirement　of　the　stiffness.　A　scale　is　developed　relatively　high　stiffness　and　high　cantilever　mechanism　composed　of　five　box,　box　at　all　levels　adopt　i-steel　design,　to　enhance　the　rigidity　and　stability.　Driven　by　a　rope　between　housing　at　all　levels,　at　the　same　time,　to　ensure　the　position　precision.　Using　the　finite　element　analysis　ANSYS　platform　the　cantilever　mechanism,　validate　the　rationality　of　the　design.　At　the　same　time　design　of　endoscopic　detection　device　charge　electric　control　system,　and　the　control　program　is　based　on　Vc++　to　develop　software.　This　set　of　equipment　has　been　successfully　applied　on　the　inner　wall　of　the　column,　detection　of　industrial　field,　has　obtained　the　good　effect.