Abstract: Multilevel accelerated Cartesian expansion algorithm (MLACEA) is applied on acceleration of method of moments to solve electrically small electromagnetic problems. Its computational complexity of matrix and vector multiplication is O(N). It is easy to combine multilevel fast multipole algorithm (MLFMA) with MLACEA, for MLACEA and MLFMA are both based on hierarchical Orc-tree data structure. Electrically large problems which contain complex and fine structure can be solved efficiently in wide band using the combined algorithm. Besides, MLACEA and MLACEA-MLFMA combined algorithm is described in detail. Memory and time consumption of MLACEA-MLFMA are compared with MLFMA by numerical experiment.