In this paper, it is proved that the problem of composite beams jointed by bolts can be solved in terms of certain equivalent continuous beams. The equivalent beam is specified as follows: 1) It consists of supports of the original beam and equivalent supports situated at the points where bolts are used. 2) It is loaded by the given load on the original beam.Then the reactions at the bolts in the original composite beam are equal to a constant C times the reactions at various supports of the equivalent continuous beam. The constant is equal to C=(E′J′-k(EJ+E′J′))/(EJ+E′J′), where EJ and E′J′ are flexaral rigidities of the first and second parts of the composite beam respectively, and k is the distributing ratio of load on the second part.The solution of the problem is then greatly simplified.This method can be generalized for composite beams consisting of more than two parts, on which the given load is not proportionately distributed.