A residue analysis method for thiamethoxam and lambda-cyhalothrin in tea infusion was established, and the influence of brewing time, brewing temperature, tea shape and residue concentration in made tea to the brewing behavior from made tea to tea infusion were investigated by this method. The results showed that: when constant temperature of 100℃ for different brewing time (5~30βmin), the brewing rate of thiamethoxam were maximum at 15βmin, which were 81.2% in whole leaf tea and 88.6% in broken tea, the brewing rate of lambda-cyhalothrin reached the maximum of 5.5% at 25βmin in broken tea, and the whole leaf tea for 0.41%; after brewing in different temperature for 15 min, the brewing rates of thiamethoxam and lambda-cyhalothrin were increased according to the brewing temperature, when the temperature was 100℃, in the whole leaf tea and in the broken tea, the brewing rates of thiamethoxam were the maximum at 83.9% and 89.1%, respectively; and for lambda-cyhalothrin were the maximum at 0.55% and 4.1%, respectively. When constant temperature at 100℃, after brewing 15 min for three times, the brewing rates of two pesticides were decreased with the brewing times, and the total maximum brewing rates of thiamethoxam and lambda-cyhalothrin were at 93.25% and 1.94%, respectively. The extracting concentration of thiamethoxam in tea infusion from made tea were meeting the linear relationship, the equation was Y=0.9267X－0.0336, R²=0.9945, and the concentration of lambda-cyhalothrin in tea infusion extracting from made tea were meeting the quadratic function relationship, the equation was Y=0.0026X²－0.0023X＋0.0096, R²=0.9765. On the basis of research, the risk assessment on thiamethoxam and lambda-cyhalothrin in tea during drinking showed that the risk to human health via tea drinking was very small.