It is well known that alcohol consumption is associated with type 2 diabetes. However, the association between age of alcohol onset (AAO) and drinking duration with type 2 diabetes among Chinese adults is not fully understood. Our study was based on the data from the China Kadoorie Biobank, which included 512,712 participants aged 30-79 years in China from 2004-2008. Cox proportional-hazard model was used to estimate the association between AAO and drinking duration with type 2 diabetes. After adjustment for potential covariates, 18.1 = AAO = 29.0, 29.1 = AAO = 39.0 and AAO > 39.0 were associated with 22% (95%CI: 14%, 30%), 25% (95%CI: 17%, 33%) and 32% (95%CI: 24%, 39%) lower hazard ratio of type 2 diabetes, compared with abstainer, respectively. Drinking duration < 10.1, 10.1 = duration = 20.0, and 20.1 = duration = 30.0 were associated with a lower risk of type 2 diabetes, compared with abstainer. Among weekly drinkers, AAO < 18.1 and drinking duration>30.0 were associated with 18% (95%CI: 9%, 33%) and 20% (95%CI: 3%, 40%) higher hazard ratio of type 2 diabetes, compared with 18.1 = AAO = 29.0 and drinking duration < 10.1, respectively. In conclusion, a decrease risk of type 2 diabetes was associated with a late AAO and a short drinking duration in the largest prospective cohort of Chinese adults. But early AAO and long drinking duration was not associated with lower risk of type 2 diabetes.