Novel deep foundation pit support pile connecting device and support pile

The utility model relates to the technical field of steel pipe piles, and provides a novel connecting device of a deep foundation pit support pile and the support pile, the connecting device comprises a lock catch I and a lock catch II which are arranged on two sides of a steel pipe, the lock catch I is a linear lock catch used for connecting the steel pipe in a linear direction or a corner lock catch used for connecting the steel pipe in a corner direction, and the lock catch II is a lock catch II. The supporting pile comprises the connecting device and further comprises a lengthening device, the lengthening device comprises a stiffening plate, flange plates and bolts, the flange plates are arranged at the two ends of each steel pipe, and the bolts are arranged at the two ends of each steel pipe. A plurality of stiffening plates are evenly arranged between the flange plates and the outer walls of the steel pipes, and the flange plates between every two adjacent steel pipes are connected through bolts. And by