The double-layer solid rotor induction machines are widely used in the field of high-speed and high-power air compressors due to its high mechanical strength of the rotor and good electromagnetic performance. However, due to the complex electromagnetic field path inside the solid rotor and the saturation effect of the rotor material, the calculation of rotor impedance is difficult. The article adopts two different analytical calculation methods, namely the multi-layer method and the equivalent permeability method, to calculate the impedance of the double-layer solid rotor, and analyzes the influence of the number of layers in the multi-layer method on the accuracy of rotor impedance calculation. The results obtained from the multi-layer method and the equivalent permeability method are compared with the finite element method calculation results, demonstrating the advantages and disadvantages of the two analytical calculation methods in terms of calculation accuracy. This provides a reference for the calculation of rotor impedance in double-layer solid rotor induction machines.