The Flatted end connector is one of the simplest joint generally used for low cost and light weight tubular space structure. There is need to improve the load carrying capacity and avoid sudden failure of such a joint. Few researchers have tried to reduce eccentricity by using spacer bar and reinforcement. In order to better utilize the steel at joint location, it is decided have the research on the beahviour of flattening angle tube. Investigation of behaviour of Flattening angle tube is main objective of the present work. Generally, member of structure checked for incremental loading. The value of factor of safety of steel structure is 1.67. If we want find design load for irregular section for a particular material. Then Firstly find allowable stress for this material and apply incremental load simultaneously compute stresses for each load and apply incremental load till to reach allowable stress. Design Flattening angle tube for incremental load and verify Flattening angle tube for each load and continuously increasing load up to get a maximum design load and thus maximum design load should be allowable stress. Analysis and design of flattening angle tube by using theories of failure. The modeling of flattening tubes has done on Catia software and imports this model in Ansys software (Workbench) for compute the shear and principal stresses. The angles of flattening angle tubes are 5°, 10°, 15°,20°, 30°, 45° and 50°. Observed maximum design (Capacity) load on each flattening angle tube.