Nuclear structure phase transitions SU(3)–U(5)–SU(3) of the yrast-band structure in 182Os nucleus are successfully described, based on the association of microscopic interacting Boson model (IBM) with the γ-ray energy on spin curves (E-GOS). It is very abstract because of lack of concrete facts. A probable explanation of these one after the other phase transitions are geometrically given, with a functional relation of microscopic parameters in microscopic sdIBM-Fmax approach and potential energy surface in Bohr collective model. It is expounded that at high angular momentum, in a well-deformed nucleus, a probable way to the γ-vibrational energy can become lower than the rotational energy bcause there are a number of degeneracy states formed by quantum effect between the highter and lower excition states so as to achieve SU(3)–U(5) structue phase transition.