The variable preconditioned (VP) Krylov subspace method with communication avoiding (CA) technique is adopted for the solver of a linear system obtained from electromagnetic analysis, and the numerical features are investigated. A massive communication time between processing units (PUs) or graphics PU/many integrated core is a big issue for parallelization efficiency that needs to be solved. Although k-skip Krylov subspace method is one solution for the issue, convergence property of the method is becoming worse. For this reason, we adopt the k-skip Krylov subspace method as inner-loop solver of the VP Krylov subspace method. The result of computation shows that the VP Krylov subspace method with CA technique is very effective for the linear system obtained from electromagnetic analysis.