This work presents the relationship between the domains of Human Factors Integration(HFI) to develop the weapon systems through integrating human factors into the defense acquisition program. The 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. In this point of view, this paper identifies and analyzes the HFI domains. Based on the results, this paper presents the relationships between the domains of the HFI.