Rheology and small angle X-ray scattering(SAXS) were used to study the effect of the content of 17R4(PO14EO24PO14) and temperature on the gel structure of the 17R4/F127(EO99PO65EO99) mixed solutions. It was indicated that the structures of sol, soft gel and hard gel were corresponding to disorder phase, disorder/cubic coexisted phase and cubic phase. With increasing temperature, hard sphere radius and aggregation number of micelle decreased. For pure 17R4, it is difficult to form micelles. However, when the temperature was increased, 17R4 chains took part in the formation of micelles and therefore the number of micelles increased, which made the number of F127 chains in one micelle decrease. Thus, the number of PEO blocks of F127 in coronal part decreased and then the coronal part became softer. As a result, a fcc-bcc transition occurred in the system with 17R4/F127 molar ratio of 2.