Abstract: A simplified two-dimension calculation model for helical magnetic flux compression generator with explosive initiated axially(AMFCG) was built by Maxwell equation. By the theoretic model the calculation formula of magnetic flux was simplified, which combined the equivalent circuit equation with magnetic flux expression. The expanding process of the explosive tube radius, the evolution process of AMFCG initial inductance and output current were simulated with three groups of parameters. The competition process between the detonation pressure and magnetic pressure was calculated and the magnetic field distribution was presented.