To determine the optimum conditions for the production of low lactose milk by enzyme method, the hydrolysis process of low lactose milk was optimized by the response surface method, with the hydrolysis rate of lactose as an index. The results were as follows: the ratio of enzyme to substrate (\[E\]/\[S\]) was 1.50‰, and the hydrolysis was undertaken at 38.15 ℃ for 3.0 h. Under these conditions, the lactose hydrolysis rate of low lactose milk was 92.67%. Moreover,14.02% of the oligosaccharides were detected by HPLC detection, which showed β-galactosidase could hydrolysis lactose and turn glycosidic.