A telescope with a foldable and extendable base that can be extended before use and folded after use, including a telescope main body being cradled in a socket; a stanchion having an upper joint connecting to a joint base of the socket; a left base having a ring with an arc external cover and a left leg on a lateral; a right base having a circular groove with an arc body and a right leg on a lateral; a sliding base having an upper hinge for connecting with a lower joint of the stanchion through a bolt and a nut; a bolt passing through the circular groove and the bolting hole of the sliding base to enable the sliding base sliding round the ring and the arc external cover sliding round the arc body.