A modulus-based matrix splitting (MMS) iteration method, which belongs to a class of inner-outer iteration methods, has been recently studied for numerically solving large sparse quasi-complementarity problems (QCPs). In order to improve the convergence rate of the inner iteration so as to get a fast convergence rate of the outer iteration, a general MMS (GMMS) iteration method is proposed in this paper. Convergence analyses on the GMMS method are studied in detail when the system matrix is either an $H_{+}$-matrix or a positive definite matrix. In the case of an $H_{+}$-matrix, a weaker convergence condition of the GMMS iteration method is obtained. In addition, two numerical experiments are conducted and the results indicate that the new proposed GMMS method achieves a better performance than the MMS iteration method.