This work describes the process to integrate human factors into the defense acquisition program management. Human Factors Integration(HFI) is a systematic process for identifying, tracking and resolving human related issues ensuring a balanced development of both technologies and human aspects of capability. To do this, this paper researches the defense acquisition program management of US and UK, and identifies the products of HFI domains through the analysis of relationship between the considerations of HFI domains. It also defines the HFI purposes of the phases of defense acquisition program, and derives HFI activities required. From results of this comprehensive analysis, HFI process in the concept phase including the activities and relationship between HFI domains is presented.