s: Mechanism of the electromagnetic field associated with loss about running cable is firstly analyzed in the paper. Based on electromagnetic field theory and Bessel function, combining with calculation of induced current on cable shield, current density distribution of cable shield under harmonic is deduced. Approaching effect and skin effect on the current density distribution is considered and the corresponding analytical expression is deduced during this process. With previous analysis of two phase cable circuit, and then leading into the correction factor, the analytic expression of the final structure is extended to multiphase cable case. The core loss, metal shielding layer loss and insulation loss is analyzed after that. Multiphase cable laying correction factors are deduced by the correction factor above. Qualitative analysis results of the influence on cable harmonic loss is got on MATLAB simulation platform and the calculation method is compared with IEC and IEEE standard furthermore.