The utility model discloses a portable automatic overlap seam car of pressure steel pipe installation, including top support frame, bottom suspension strut, directaxis, go up skeleton, skeleton and walking trolley down, top support frame and bottom suspension strut parallel arrangement, tapered roller bearing and top support frame's central rotatable coupling is passed through to the upper end ofdirectaxis, the lower extreme of directaxis passes through the central rotatable coupling of tapered roller bearing and bottom suspension strut, goes up skeleton and skeleton parallel arrangement downbetween top support frame and bottom suspension strut, and with directaxis walking trolley 1, the outer walking trolley 1 that follows of walking trolley and last skeleton and lower skeleton. The utility model relates to a portable automatic overlap seam car of pressure steel pipe installation passes through the cooperation between support frame and the skeleton, realizes that walking trolley canfollow directaxis 360 and rotate, realizes reciprocating of work platform through walking trolley simultaneously to can be under construction to pressure steel pipe's more multiposition under the condition that the minimize removed, can effectual promotion work efficiency.