Starting from 2,4-dichlorobenzoic acid, 4-amino-5-(2,4-dichlorophenyl)-2H-1,2,4-tria- -zole-3(4H)-thione 4 was afforded in four steps including esterification, hydrazidation, salt formation, cyclization. 5-(2,4-dichlorophenyl)-4-( substituted methyleneamino)-2H-1,2,4-triazole- 3(4H)-thione 5 was then synthesized by the condensation reaction of the intermediate 4 with substituted formaldehyde. Eight schiff base sulfur ether derivatives containing 1,2,4-triazole unit in yield of 69%~78% were synthesized by reaction of 5-(2,4-dichlorophenyl)-4-( substituted methyleneamino)-2H-1,2,4-triazole-3(4H)-thione with halogenated hydrocarbon using K2CO3 as catalyst in acetonitrile at 75℃ for 2 h. The structures were confirmed by 1H NMR, 13C NMR, 19 F NMR, IR and elemental analyses. The preliminary bioassay showed that the antifungal activity of some compounds to P.cubensis at the concentration of 100 mg/L was 100%。