Telescopic supporting device and working machine

The invention provides a telescopic supporting device and an operation machine. The telescopic supporting device comprises a telescopic arm; the supporting leg is fixedly connected with the telescopic arm; a turret base in which a leg box for accommodating the telescopic arm is formed; the telescopic arm can telescopically move relative to the supporting leg box; a supporting plate in contact fit with the bottom of the telescopic arm is arranged at the bottom of the inner side of the supporting leg box. Thus, no matter how the telescopic arm stretches out and draws back, the force bearing point of the turret base is kept on the supporting plate all the time, and therefore the telescopic arm is prevented from making contact with a weak area at the bottom of the supporting leg box, stress deformation of the bottom of the supporting leg box is reduced, and the structural safety of the supporting leg box is improved. Meanwhile, the lap joint position of the telescopic arm and the landing leg box is always on the