Abstract: The field trial of residue level and degradation dynamics of Metalaxyl-M in tobacco and soil were carried out in Shandong and Hunan during 2005-2006.The results showed that the degradation speed of meta-laxyl-M in tobacco leaves was faster than in soil,its half-life periods were 1.2 to 1.5 days in tobacco leaves and 6.4 to 2.8 days in soil.By applying 3 to 4 times with the guide dosage,the pesticide residue in leaf was less than 2 mg/kg in 14 days after the last application.It was suggested to end the application of Metalaxyl-M at least 21 days ahead of tobacco harvest for safety's sake.