Abstract: In the life of the state in Indonesia in accordance with the provisions in the 1945 Constitution, Indonesia does not adhere to trias politic’s teachings with the separation of powers. Inter-agency relationships are based on the principle of power-sharing contained in the 1945 Constitution. In the development of state institutions in Indonesia must be consistent in performing their functions amid the increasingly complex of modern state activities, the more institutions or equipment needed. Tools or institutions that are created through the constitution are often no longer able to accommodate specific tasks that generally, require independence and professionalism in the implementation. In the 1945 Constitution of the State of the Republic of Indonesia (the 1945 Constitution) before the amendment, there are six highest/highest state institutions, namely the People’s Consultative Assembly as the highest state institution; as well as DPR, president, MA, BPK and DPA as state high institutions. However, after changing the 1945 Constitution (Amendment), it is stated that the state institution is affiliated with the MPR, DPR, DPD, president, BPK, MA, MK and KY without knowing the term of the highest or the highest state institution. This study tries to provide an overview of the implementing social engineering model in relationship between state institutions in Indonesia amid the complexity of state activities in Indonesia.