Blooms of the Microcystis aeruginosa in water have been a long-standing problem for water quality and a human-health issue. Public concern for the inhibition of Microcystis aeruginosa has become increasingly urgent. AgBiO3 is an algaecide having good inhibitory effects on the growth of Microcystis aeruginosa with hydroxyl radicals generated by photocatalyst. The inhibition of Microcystis aeruginosa exposed to AgBiO3 was optimised using statistically-based experimental designs. The four variables, namely, ZnSO4, CaCl2, CuSO4 and NaNO3, were screened as significant effects and were further optimised to determine the optimum levels and their interactions. The optimal concentrations of variables for maximum inhibition were 0.24 mg/L ZnSO4, 125.94 mg/L CaCl2, 0.28 mg/L CuSO4 and 600 mg/L NaNO3. The maximum inhibition rate predicted by the model was 61.86%, in near-perfect agreement with the experimental value (60.07%), and significantly better than unoptimised medium (42.79%).