The confessional policy of the Russian state concerning Siberian tatars in XVII - the beginning of XX century is investigated in this work. The state policy was diverse: it varies from methods of direct violence to the loyal relation, uses islam in political interests. It is marked, that the laws were directed on supporting rights, privileges and protection of representatives of the state religion, i.e. orthodox. The certain results in christianisation of Siberian tatars were achieved due to support of orthodox church. At the same time the materials testify, that the task, put by government, to assimilate and russify Siberian tatars practically was not decided.