Nigeria is a Federal Republic modeled after the United States, with executive power exercised by the president and with influences from the Westminster System model in the composition and management of the upper and lower houses of the bicameral legislature. However, the President of Nigeria is both head of state and head of government, and of a multi-party system. Nigerian politics takes place within a framework of a federal, presidential, representative democratic republic, whereby Executive power is exercised by the government. Legislative power is vested in both the government and the two chambers of the legislature, the House of Representatives and the Senate. Together the two chambers make up the law-making body in Nigeria called the National Assembly. The highest judiciary arm of government in Nigeria is the Supreme Court of Nigeria. Nigeria also practices Baron de Montesquieu's theory of the separation of powers. The National Assembly serves as a check on the executive arm of government.
This is Nigeria system Of government in brief, you can read about other " Systems of government ' here.