Abstract: In order to improve the labor-saving degree of chemical control of weeds in rice fields and reduce the cost of weed control, metolachlor + bensulfuron-methyl 20% effervescent tablets were prepared by the dry pressing process. The type and dosage of adjuvants in the formulation were selected by the single variable method, and the field efficacy of the prepared effervescent tablets was evaluated. The results showed that the optimal formulation (mass fraction) of metolachlor + bensulfuron-methyl 20% effervescent tablets was: 16% metolachlor, 4% bensulfuron-methyl, 18% organobentonite, 9% white carbon black, 20% tartaric acid, 20% sodium bicarbonate, 6% EFW, 4% G202 and 3% magnesium stearate. The effervescent tablets could effectively control weeds in the rice field in the dosage range of 120-180 g/hm² of active ingredients, and its control efficacy was significantly better than that of single agent, which was equivalent to that of the registered wettable powder. The duration of control efficacy was more than 40 days. The effervescent tablets prepared in the study had smooth surface, no dust, and remarkable control efficacy against weeds in the rice field, which was worth to be promoted as a convenient and time- and labor-saving pesticide formulation.