The invention discloses an integral combining and hoisting in-position technology for a two-pass boiler rear water upper part. The technology comprises the construction steps that firstly, combination pre-preparation is conducted; secondly, furnace arch tube panels, an inner structure, rear water vertical small sheets and a rear water outlet header are combined in a combination site; thirdly, a rear water hanging tube outlet header and a hanging tube are combined on a boiler 30-meter temporary bracket platform; fourthly, furnace arches are spliced to simulate platform manufacturing; fifthly, the rear water vertical small sheets and the rear water outlet header are secondarily combined; sixthly, furnace arch inlet header big opening welding and pre-storing are conducted; seventhly, furnace arch assembly inner frame installation is conducted; eighthly, a rear water vertical tube panel assembly and a furnace arch assembly are secondarily combined; ninthly, the rear water hanging tube outlet header, the hanging tube assembly, the furnace arch tube panels and a frame assembly are fixed in a penetrating manner; tenthly, the lower portion of the rear water hanging tube assembly and the rear water outlet header are combined and welded; eleventhly, assembly rigidity and soft strengthening is conducted; and twelvethly, integral assembly hoisting is conducted in place. According to the integral combining, hoisting and in-position technology, when a spare part hoisting method is selected, the occupied time for field large hoisting machines is effectively shortened, the occupation frequency for the field large hoisting machines is effectively reduced, and meanwhile the aerial operation workload is directly reduced.