The invention discloses a removal-free template on the inner side of a concrete base of an anti-collision guardrail, and an application method thereof. The application method includes an earlier preparation step and a placing step, wherein the preparation step includes the following operation: taking a precasting thin plate as an inner side template of the concrete base of the guardrail, adopting a square timber and an anchor bolt to limit one side of the precasting thin plate, adopting cushion blocks bound on a rebar of the guardrail base to limit the other side of the precasting thin plate, placing an inflation capsule in a gap of the square timber, adopting the inflation capsule to seal the clearance between a beam top and the precasting thin plate to avoid slurry leakage, and adopting a back pressure screw cap at the top of the anchor bolt and a cord chain encircling the guardrail base to limit the square timber; then the placing step of placing concrete at the guardrail base is performed on the spot; and after the placing is completed, the precasting thin plate is combined with the concrete of the guardrail base. According to the invention, the capability of resisting corrosion of deicing salt is guaranteed, the construction speed of the guardrail base is quickened, and the precasting thin plate is easy to replace during the operation.