The invention discloses a reflective strip attaching device. The reflective strip attaching device comprises a base plate, a supporting block fixed on the back upper part of the base plate, and an upper support, wherein one end of the upper support is fixedly connected with the upper side of the supporting block while the other end of the upper support is fixedly connected with a fixed assembly; and a first air suction cavity is formed in the upper support, and the tail end of the first air suction cavity is connected with an air suction connector in the right rear end of the upper support. The fixed assembly is formed by fixedly connecting an upper fixed seat and a lower fixed plate; a second air suction cavity is formed in the fixed seat, and the second air suction cavity is communicatedwith the first air suction cavity. The front side of the fixing plate is provided with an adsorption groove, and a plurality of arc-shaped grooves leading to the second air suction cavity are formedin the adsorption groove. According to the device, the problems that a reflective strip of an existing hand-push type sticker cannot be tightly attached, warping reflecting strips cannot be assembled,the assembling efficiency is very low, and when the reflecting strips are attached to the lower cover of a U-shaped structure, the operation difficulty is higher, and the percent of pass is very lowcan be solved. The production efficiency is greatly improved.