One of the concerns for Iranian society has been to establish order and security. After the Constitutional Revolution, the meddling by Britain and Russia has been added to the main factors of threat to the order and security in Iranian society. As the result of World War II and continuing unrests, Russia and Britain adopted some measures for their interests and the security of their agents. Russia located its troops in the northern regions of Iran, from Azerbaijan to Khorasan. But instead of direct military presence, Britain formed South Persia Rifles. By using analytical-historical method and respective sources and documents, this research examines the factors of formation of this force and its measures and consequences. The results indicate that the British Government formed this police in order to preserve its oil resources, confront German agents, provide security for its agents and preserve its commercial interest. Although the formation of this police force by Britain was in the name of Iran, but it faced reaction from Iranian government and people.