To complete stress-strain test of large size block, a new-style slick pole self-lock 3-axial machine was designed, beam to move freely or lock itself was realized by hydraulic means, the beam lifting motion and accurate positioning were solved. The designed hydraulic system could be used to realize beam lifting motion and accurate positioning, the preload and unloading, opening elastic sleeve, interference elastic sleeve opening and locking action. Alternate motion of interference elastic sleeve with the upright post connecting to open up and a locking opening elastic sleeve and the lifting cylinder, beam “unlimited” lead was realized.