In this paper, the optimized doping condition of crystalline silicon solar cells with 156 × 156㎟ area was studied. To optimize the drive-in temperature in the doping process, the other conditions except variable drive-in temperature were fixed. These conditions were obtained in previous studies. After etching 7㎛ of the surface to form the pyramidal structure, the silicon nitride deposited by the PECVD had 75∼80㎚ thickness and 2 to 2.1 for a refractive index. The silver and aluminium electrodes for front and back sheet, respectively, were for medby screen-printing method, followed by firing in 400-425-450-550-850℃ five-zone temperature conditions to make the ohmic contact. Drive-in temperature was changed in range of 830℃ to 890℃ to obtain the sheet resistance 30∼70Ω/□ with 10Ω/□ intervals. Solar cell made in 890℃ as the drive-in temperature revealed 17.1% conversion efficiency which is best in this study. This solar cells showed 34.4 ㎃/㎠ of the current density, 627 ㎷ of the open circuit voltage and 79.3% of the fill factor.