7-hydroxy-4-methyl coumarin is an important chemical intermediate. DT-852 macroporous sulfonic acid resin is developed as efficient catalyst in synthesis of 7-hydroxy-4-methyl coumarin technology. Results show: DT-852 macroporous sulfonic acid resin has well catalytic activity; The better synthesis conditions for 7-hydroxy-4-methyl coumarin were: reaction temperature 105 oC and reaction time 2.5 h, 1.0 g catalyst, material ratio ethyl acetoacetate to resorcinol 1.0, the yield was 93.8%, w (7-hydroxy-4-methyl coumarin) = 98.27% (HPLC). Catalyst can be reused many times. Product was verified with mp and IR.