Abstract: This paper analyzes optimal energy efficiency of the merger and acquisitions of industrial groups by introducing the views on the optimal ways in which animals search for food originally,bringing forward optimal strategy.First of all,the paper gives basic assumptions of models.Secondly,it sets up the models which discuss optimal strategy for merging an upstream firm and a downstream firm,respectively,and gives the sufficient conditions for increasing energy efficiency.Finally,it sets up the model which discusses horizontal mergers and gives the sufficient conditions for increasing energy efficiency and presents an example to illustrate how to make decision.The results of it can be applied to the merger and acquisitions of industrial groups in China.

Key words: Industrial group, energy efficiency, strategy, merger and acquisition