The invention discloses a manufacturing method of a double-twist box-shaped bent member. The double-twist box-shaped bent member is formed by assembling and welding an upper flange plate, a lower flange plate, two side webplates, a transverse partition plate, a longitudinal partition plate and a strengthening rib. The manufacturing method comprises the following steps: 1, preparing four plane steel plates; 2, pressing the upper flange plate, the lower flange plate and the two side webplates; 3, manufacturing the transverse partition plate, the longitudinal partition plate and a strengthening rib plate; 4, manufacturing an assembling and welding positioner; 5, installing and bonding the lower flange plate on the positioner; 6, preheating the plates; 7, positioning and welding the transversepartition plate, the longitudinal partition plate and the strengthening rib on the lower flange plate; 8, installing and welding the upper flange plate at the top of the partition plate; 9, respectively installing and welding the two side webplates at both sides of the transverse partition plate; 10, detecting, repairing, polishing and rectifying the whole member; 11, carrying out the defect detection, the sand spraying and the rust removal of the member; 12, painting. The manufacturing method is suitable for manufacturing the double-twist box-shaped bent member with a plate thickness of 20-90mm and a twist degree of 0-30 degrees in factories.