With new models of AMI solar spectra and Si refractive indices in the wavelength range of 0.4 mumless than or equal togimelless than or equal to0.97 mum, effective absorption powers of Si solar cells coated with the single and double AR layers were theoretically calculated for the first time. The SiO2, Si3N4 and SiO2/Si3N4 easily obtainable in the standard Si process were used as the AR layers of Si solar cell. Optimum thicknesses showing the maximum absorption power for AR layers Of SiO2, Si3N4 and SiO2/Si3N4 were as follows: d(SiO2)=1000Angstrom, d(Si3N4)=700Angstrom and d(SiO2/Si3N4) =500 Angstrom/300Angstrom Effective absorption powers in the solar cells Of SiO2-Si, Si3N4-Si and SiO2/Si3N4-Si were 520W/m(2), 565W/m(2) and 607W/m(2) at AM1 in the optimum conditions of AR coating, respectively.