Abstract: Abstract: Eight derivatives of 4-methyl-coumarin were synthesized, and their pesticidal activities were determined in this paper. First, 4-methyl-7-hydroxy-coumarin was prepared from ethyl acetoacetate and resorcinol by Pechmann reaction. Then 4 kinds of 4-methyl-7-acyloxy-coumarins were obtained by acylation of 4-methyl-7-hydroxy-coumarin with different chlorides. Finally, 4 kinds of 4-methyl-7-acyloxy-coumarin occurred Fries rearrangement to give 4-methyl-7-hydroxy-8-acyl-coumarin catalyzed by anhydrous AlCl3. The antifungal and herbicidal activities were determined by methods of mycelium growth rate and seed germination respectively. The results indicated that six derivatives of 4-methyl-coumarin had certain antifungal activity against all the 4 kinds of plant pathogens tested. The antifungal activity of 4-methyl-7-hydroxy-8-benzoyl-coumarin was the best of the six chemicals, with EC50 of 62.40 and 69.22 mg/L against Valsa mali and Coniothyrium diplodiella respectively. Followed was 4-methyl-7-hydroxy-8-o-fluorobenzoyl-coumarin. Herbicidal activities of the synthesized compounds against the root and stem development of Amaranthus retroflexus and Lactuca sativa seedlings were weak.