In order to improve the photoelectric conversion efficiency of n-type interdigitated back contact (IBC) solar cells, the selective emitter structure was prepared by screen printing boron paste and high temperature diffusion, the effects of boron diffusion and screen printing on the passivation and contact properties of the cells were studied. The experimental results show that when the deposition time and annealing time of boron diffusion remain unchanged, the BBr3 flow rate is 100 mL/min, the deposition temperature is 830 ℃, and the annealing temperature is 920 ℃, the implied open circuit voltage of light doping emitter (p+) reaches 710 mV, and the dark saturation current density reaches 12.2 fA/cm2. When the consumption of the locally printed boron paste at the emitter is 220 mg, after high temperature annealing on boron diffusion, the implied open circuit voltage of heavily doping emitter (p++) remains at about 683 mV, the sheet resistance is only 46 Ω/□, and the metal contact resistance is 2.3 mΩ·cm2. The highest photoelectric conversion efficiency and average photoelectric conversion efficiency of IBC cells prepared by this process are 24.40% and 24.32%, compared with the IBC cells before optimization, the conversion efficiency is improved by 0.28 percentage points.