In this paper, we systematically studied the thermoelectric power factor of Bi2O2Se when doped with a total of 21 main group elements. This was achieved using first principles density functional theory combined with semi-classical Boltzmann transport theory. Starting from the integral factor in Mott's formula, we thoroughly examined the thermoelectric power factor that was determined from the electronic structure. We also determined the mechanisms of action of temperature and carrier concentrations on these properties. The results show that there are different optimization strategies for the density of states (DOS) with different shapes around the Fermi level. The unconventional behaviours of the Sn, In and Tl doping cases are discussed. The present work uses a theoretical approach to study the effect of doping elements on the thermoelectric power factor of Bi2O2Se, which is valuable for optimizing its desired properties.