In order to realize efficient transport-burnup coupling calculation,a new calculation method based on splicing fission matrix theory is proposed in this paper.The combined fission matrix method enables to obtain the system fission matrix from a pre-calculated database,and then the database matrices are combined according to the actual conditions of the calculation model and the properties of the terminal area.The fission matrix database is obtained by Monte Carlo fixed source calculation,and the core calculation does not need Monte Carlo simulation,so the time-consuming critical calculation can be avoided.In this paper,the effective multiplication factor and fission source distribution of a typical two-assembly model with a burnup up to 600EFPD are obtained.The burnup-enrichment composite correction ratio can reduce the root-mean-square error of the fission source to less than 0.7%,thereby confirming the feasibility of this algorithm.