The invention discloses a vibration-reducing turnout track gauge adjustable structure. The structure comprises a base plate, a steel rail and a guardrail, wherein the steel rail and the guardrail are arranged on the base plate. Fixing holes are formed in the base plate, and the base plate is fixed in the mode that base plate fixing bolts penetrate through the fixing holes. The structure further comprises gauge adjusting cover plates, the gauge adjusting cover plates are arranged in the fixing holes in a rotatable adjusting mode, through holes through which the base plate fixing bolts penetrate are formed in the gauge adjusting cover plates, and the through holes are eccentrically formed in the gauge adjusting cover plates. The adjustable structure is reasonable in design, when the turnout track gauge is adjusted, the structure of the fixed steel rail does not need to be disassembled completely, it is only required that the base plate fixing bolts are unscrewed to rotate the gauge adjusting cover plates, and adjusting can be completed. The adjusting operation is simple, the adjusting efficiency is high, and the adjusting accuracy is easy to control.