To simplify the computational process and improve the calculation efficiency， a fast evaluation method of component importance coefficients based on the quasi-balanced matrix， which was derived from the stiffness-based component importance evaluation method， was proposed for spatial structures. By transforming the balanced matrix， the quasi-balanced matrix containing the length information of components was obtained. When the linear stiffness of each component was approximately equal and the effect of structural stress stiffening was not considered， the global tangential stiffness matrix was simplified， and the component importance coefficients were expressed only including the quasi-balanced matrix. The singular value decomposition of the quasi-balanced matrix was carried out， and the mathematical relation between the eigenvalues of the stiffness matrix and the singular values were established. Taking the product of singular values as a response， the expression of the component importance coefficient was modified so as to calculate it. Through case study on three truss examples， it was proved that the calculation results of the evaluation method of component importance coefficients based on the quasi-balanced matrix are consistent with the stiffness-based evaluation method， which shows that the proposed method is a practical and fast calculation method.