A check device for checking a brake disc and a tire tread surface of a vehicle, characterized in that the check device comprises: a check device body; and a base comprising a first base body, a second base body, and a locking mechanism, wherein the check device body is mounted to the first base body; wherein the first base body has a hollow structure, and at least part of the second base body can be accommodated in an inner cavity of the first base body; the first base body comprises a first sliding member, the second base body comprises a second sliding member, the first sliding member cooperates with the second sliding member to move the second base body with respect to the first base body, and at least part of the second base body can be accommodated in or can extend out of the inner cavity of the first base body; the locking mechanism is used for locking the second base body with respect to the first base body such that the at least part of the second base body is accommodated in the inner cavity of the first base body, and unlocking the second base body with respect to the first base body such that the at least part of the second base body extends out of the inner cavity of the first base body; the check device being characterised in that the first base body comprises an upper cover, and the upper cover is covered on the first sliding member; the locking mechanism comprises a track groove, a rotating groove, a rotating shaft, and a locking block; wherein the track groove is provided on an inner surface of the upper cover, the upper cover extends into the track groove with a locking table, the rotating groove is provided on the second sliding member, one end of the rotating shaft is accommodated in the rotating groove, the rotating shaft can rotate with respect to the rotating groove, the locking block is fixed to the other end of the rotating shaft, the locking block is provided with a locking groove, the locking block is accommodated in the track groove, and when the second base body moves with respect to the first base body, the locking block can move along the track groove and rotate; and when the second base body is accommodated in the inner cavity of the first base body and the locking block is inclined with respect to the track groove and the locking groove is engaged with the locking table, the locking mechanism locks the first base body and the second base body, and the second base body cannot protrude from the inner cavity of the first base body; when the locking groove is disengaged from the locking table and a notch of the locking groove is rotated to a direction deviating from the locking table, the first base body and the second base body are unlocked so that the second body can protrude from the inner cavity of the first base body. a check device body; and a base comprising a first base body, a second base body, and a locking mechanism, wherein the check device body is mounted to the first base body; wherein the first base body has a hollow structure, and at least part of the second base body can be accommodated in an inner cavity of the first base body; the first base body comprises a first sliding member, the second base body comprises a second sliding member, the first sliding member cooperates with the second sliding member to move the second base body with respect to the first base body, and at least part of the second base body can be accommodated in or can extend out of the inner cavity of the first base body; the locking mechanism is used for locking the second base body with respect to the first base body such that the at least part of the second base body is accommodated in the inner cavity of the first base body, and unlocking the second base body with respect to the first base body such that the at least part of the second base body extends out of the inner cavity of the first base body; the check device being characterised in that the first base body comprises an upper cover, and the upper cover is covered on the first sliding member; the locking mechanism comprises a track groove, a rotating groove, a rotating shaft, and a locking block; wherein the track groove is provided on an inner surface of the upper cover, the upper cover extends into the track groove with a locking table, the rotating groove is provided on the second sliding member, one end of the rotating shaft is accommodated in the rotating groove, the rotating shaft can rotate with respect to the rotating groove, the locking block is fixed to the other end of the rotating shaft, the locking block is provided with a locking groove, the locking block is accommodated in the track groove, and when the second base body moves with respect to the first base body, the locking block can move along the track groove and rotate; and when the second base body is accommodated in the inner cavity of the first base body and the locking block is inclined with respect to the track groove and the locking groove is engaged with the locking table, the locking mechanism locks the first base body and the second base body, and the second base body cannot protrude from the inner cavity of the first base body; when the locking groove is disengaged from the locking table and a notch of the locking groove is rotated to a direction deviating from the locking table, the first base body and the second base body are unlocked so that the second body can protrude from the inner cavity of the first base body.