To solve the problem that the existing effective width formula of the equivalent strut mode does not apply to steel frame structure with light enclosure wall panels, in this paper, re-fitting the effective width formula of the equivalent strut model for steel frame structure with light enclosure wall panels is obtained by parameter analysis method. Considering the key parameters influencing lateral stiffness of steel frame with light enclosure wall panels on the applicability of formula, the validity of the formula was proved by using the test data in the literature. The results show that the fitted formula are applicable in different cross-height ratio, axial load ratio, wallboard thickness and wallboard holes. In different width wallboard, it can be multiplied by the width coefficient KB to regulate the influence of the formula by panel width.