The invention provides a construction method for casting a continuous beam in situ by moving formworks longitudinally and transversely. The method comprises a formwork transverse moving construction sub-method and a formwork longitudinal via-hole moving construction sub-method. The formwork transverse moving construction sub-method comprises the four main steps including outer rib rotating; formwork transverse moving; connecting between main beams and piers; and restoration of the outer ribs. The longitudinal via-hole moving construction sub-method comprises the five main steps including outerrib rotating for jacking up the main beams; primary formwork longitudinal moving; frontward moving of a rear main supporting leg; frontward moving of a front main supporting leg; and secondary formwork longitudinal moving. By means of the construction method provided by the invention, transverse and longitudinal formwork moving can be fast completed under an adverse construction environment, theconstruction period can be shortened, the formworks do not need to be dismounted and mounted again, construction operation is facilitated, and the construction safety is improved while the construction cost is lowered.