A series of new acylthiourea derivatives were synthesized and characterized. The results of preliminary herbicidal activity tests showed that most compounds had good herbicidal activity against Digitaria adscendens and Amaranthus retroflexus, especially for compounds 4b (N-(2-chloro-4-methylsulfonylbenzoyl)-N’-(2-chlorophenyl) thiourea) and 4f (N-(2-chloro-4-methylsulfonylbenzoyl)-N’-(2,3-dichlorophenyl) thiourea). In vivo acetylhydroxylate synthase (AHAS) enzyme activity inhibition tests showed that all compounds had inhibitory activities against the enzyme at a concentration of 100 mg·L−1, with the highest inhibition rate up to 37.05% (compound...