The article deals with objective preconditions of forming stable bases of the cluster theory and its specific features, the attention is paid to historical aspects of dialectical development of the cluster theory. The authors highlighted the main tasks, accomplishment of which is necessary for achieving an effective cluster policy in the system of the national economy. The opportunity of using the advantages and potential opportunities of clusters in respect of the agricultural sphere of the national economy is grounded. The model of agro-industrial clusters is considered as one of the ways to increase competitive advantage of the agro-industrial complex, to achieve reproduction on an enlarged scale and to solve tasks of the national victualling. An algorithm of analyzing factors of forming clusters in the agricultural sector of russian economy is proposed.