Abstract: Distribution of magnetic field in electromagnetic continuous casting process of Al-alloy hollow billets is studied by way of numerical simulation. A two-dimensional axis-symmetric finite element model is established including relevant water-cooled core, outer mould, ingot, inner and outer induction coils. The spatial distribution of magnetic induction is determined by solving the differential equations of magnetic vector potential. Calculated results show that during electromagnetic casting the inner and outer induction coils interact with each other, and the distribution of magnetic induction is found more homogeneous when the outer induction coil current is set to about a half of inner induction coil current. The frequency and phase of coil current are important parameters during electromagnetic casting of hollow billets, the magnetic induction on inside wall surface of pipe increases notable if increasing appropriately the frequency, while the phase will affect the magnitude and direction of magnetic induction gradient.