For the study of sheath induced voltage of multi-circuit single-core power cable lines in parallel influencing on cable operation security and personal safety, a new algorithm suitable for sheath induced voltage of multi-circuit single-core power cable lines in parallel is proposed. Based on the electromagnetic coupling principle, by modeling and calculating, every cable line’s current distributed from the load current is gained firstly, then based on the results of current distribution, the calculation of sheath open induced voltage and maximum induced voltage along the sheath for every sheath grounding method are derived. With double-circuit cable lines in parallel as example, the new algorithm and the algorithm existed in the literature are both applied to several typical phase sequence arrangement methods, and the two theoretical calculation results are both calculated by programming, then the results of digital simulation for reference, the error size of the two theoretical calculation are compared and analyzed, proving the correctness of the new algorithm. By analyzing the influence of several factors on the sheath induced voltage the followings are found: relative to the single cable, the sheath induced voltage of multi-circuit single-core power cable lines in parallel may increase a lot, choosing the cross grounding method and the triangle disposition phase sequence arrangement can significantly reduce sheath induced voltage of multi-circuit single-core power cable lines in parallel.