Abstract: Internal stretch forming space lattice structure(ISFSL),composed of upper chord,lower chord,vertical web member and lateral support member,is a novel space structure.As a key bearing member of ISFSL,the upper chord ring beam is a cross center of all upper chord beams.When a new type of construction method-tensioning group by group and step by step being chosen,the internal force increasing and decreasing on structural members belonging to different group inevitably comes into being,which is different from the method tensioning simultaneously.And properly reinforced upper chord ring beam will weaken the force different in a great extent.Aiming at putting it into practice,the paper makes a detail analysis on structural force affected by upper chord ring beam.