The invention relates to an installation and construction technology for an arched-door-shaped cable-stayed bridge steel leaning tower. The installation and construction technology comprises a stress distribution and linear double control technology adopted in studying variable cross-section arched-door-shaped steel leaning tower construction based on finite element modeling, a support-free oblique pulling and buckling method installation technology for a variable cross-section arched-door-shaped steel leaning tower and a support-free precise closing technology for the variable cross-section arched-door-shaped steel leaning tower in a complex stress state. The installation and construction technology for the arched-door-shaped steel leaning tower is characterized in that in the installation process of the steel leaning tower, by means of stay cables of a cable-stayed bridge, steel tower piles are installed section by section, and the cables are hung section by section. The problems that large bridge main tower construction stress and deformation are hard to control, the requirement for construction precision is high, the construction period is tight, and heavy tasks exist are solved, and the beneficial effects of being simple in construction process and easy to operate are achieved.