The invention discloses a real-time measuring apparatus and a real-time measuring method for large deformation and stress of a test tube in steel pipe bending deformation. The measuring apparatus comprises an oil cylinder, a hydraulic system, a pressure sensor, a water pressure system, a movable side force arm, the test tube, a strain meter, a rotation-angle measuring apparatus for a 2D length position at the middle of the test tube, a transition ring, a connecting flange, a fixed side force arm, a rotation-angle measuring apparatus for a tube end of the test tube, an adjusting joint, a load-bearing beam, a control system, a computer data acquisition and processing system, a stress and strain measurement system and a draw-wire displacement sensor III. The apparatus can increase measuring stability and measuring accuracy. The measuring method realizes automatic control, real-time supervision and automatic measurement of a steel pipe bending deformation test, can fully monitor and record changes of load, displacement, rotation angle, distribution of the stress and the strain when the test tube occurs bending deformation while bearing internal pressure load and bending load at the same time, can acquire, record and display test data in time, and can analyze and treat the test data.