Considering the absorption of the nonlinear medium to the second-harmonic (SH) wave and using the complete boundary conditions for the reflections of the fundamental and SH waves at the input and output faces of the nonlinear medium, a formula for calculating the second-harmonic power generated in the absorbing and birefringent nonlinear medium was derived from the Maxwell's equation that the SH field E2 satisfies. The result shows that the formula for calculating the second-harmonic power generated in the nonzero absorption medium can be used for calculating the second-harmonic power generated in the absorptive medium if the complex refractive index, instead of the ordinary refractive index is used.