The invention provides a variable-width movable construction platform and relates to the field of bridge engineering construction. The variable-width movable construction platform comprises at least two variable-width triangular trusses, a panel is laid on the variable-width triangular trusses, at least one cantilever plate is arranged on the panel, each variable-width triangular truss comprises an upper chord, a first diagonal and a second diagonal, the two ends of the second diagonal are respectively and movably connected with the front end of the first diagonal and the upper chord, a vertical bar is arranged between the first diagonal and the upper chord, a hydraulic brace bar is arranged between the second diagonal and the upper chord, telescopic mechanisms are respectively arranged on the second diagonal and the upper chord, and the second diagonal and the upper chord can extend and retract along the axial direction of the upper chord under the effect of the telescopic mechanisms. Since the telescopic mechanisms are arranged and the second diagonal and the upper chord are connected through a pin, by disassembling and assembling the pin, changing the structure system and extending or shortening bar members, the width change of the construction platform can be realized. The variable-width movable construction platform has the advantages that the demands of construction environments with greater width change can be met, the application scope is wide, the construction progress is improved and the construction cost is reduced.