Abstract: Arc is the energy source for molten pool metal melting in arc welding process, and the split anode method is one of the effective methods to measure the energy density of the arc on the anode directly. The conventional split anode method is based on axisymmetric structure of the arc, and it is unfit for anode current density measurement of non-axisymmetric arc. A new method is proposed by measuring the current of the split anode on two perpendicular paths separately. A parameter was introduced to describe the degree of the arc asymmetry. Elliptic ring segmentation was carried out to calculate the anode current density distribution of the arc, and the split anode method was modified. The modified split anode method was verified by a pre-set two-dimensional Gaussian distribution current density model. The experimental results show that the modified split anode method can effectively calculate the anode current density distribution of the arc. The anode current density distribution of non-axisymmetric side-compressed plasma arc was measured by the modified split anode method. Compared with the x direction, the side-compressed plasma arc is compressed obviously in the y direction, showing a typical non-axisymmetric structure.