The utility creatively provides an over -and -under type cantilever crane device, including cantilever crane body, the lower festival be connected with the upper segment section of this body couplingof cantilever crane, with the base section and middle section section, middle section section upper portion suit is in the outside of upper segment section lower part, and the two is connected througha connection structure detachable, lower section upper portion suit is in the outside of middle section section lower part, and the two is connected through the 2nd connection structure detachable. The utility model discloses the creation changing fixed column cantilever crane stand among the prior art into sleeve over -and -under type stand, and stand column design becomes the three section structure, and per two sections are fixed through wearing to establish the fixed axle, rise and reduce the stand very swiftly to make things convenient for, and easy operation, behind the fixed axle, eachsection is accomodate together under dismantling, and occupation space is little, the directly transported of being convenient for.