Abstract: 2,4-Diamino-6-substituted amino sulfonyl quinazolines generally were prepared by refluxing 2,4-diamino-6-chloro-sulfonylquinazoline sulfate with suitable amines in dilute ethanol. For 2,4-diamino-6-(2-pyridy) amino sulfonyl quinazoline, it was prepared in dry pyridine. Compounds Ⅰ₂, Ⅰ₉ and Ⅰ₁₀ were shown to be more active against chloroquine resistant strain of P. berghei than sensitive strain. Compounds Ⅰ₂, Ⅰ₁₂ and Ⅰ₁₃ showed prophylactic action against P. yoelii.