The invention discloses an embedded comb plate telescopic device and an application method thereof. The embedded comb plate telescopic device comprises a first moving comb plate, a second moving combplate, a stilling comb plate, a shock absorption rubber supporting seat, a fastening screw, anchoring devices, a stainless steel sliding plate and a water stop; the first moving comb plate is embeddedin concrete of an abutment, the second moving comb plate is connected with the first moving comb plate through the fastening screw, the stilling comb plate is parallel to the road surface and connected with the abutment on the other side through the concrete, gaps for meeting the transverse displacement of a bridge are reserved between combs of the mutual cooperation of the first moving comb plate, the second moving comb plate and the stilling comb plate in the transverse direction of the bridge surface; the stainless steel sliding plate is located below the abutment on one side of the stilling comb plate and used for sliding of the first moving comb plate; the shock absorption rubber supporting seat is located between the first moving comb plate and the second moving comb plate; the anchoring devices are connected to the upper surface and the lower surface of the first moving comb plate and used for connecting the concrete; and the anchoring devices are further connected to the lowersurface of the stilling comb plate.