In this paper， the extraction technology and bioactivity of polyphenols from sweet potato leaves were studied. Prior to single factor research， the Box-Behnken experimental design combined with response surface modeling were used to optimize the extraction condition for polyphenols from sweet potato leaves. Four independent variables were tested for the response surface experiment， including volume fraction of ethanol (A)， temperature (B)， solid-liquid ratio (C)， and extraction time(D). The main components of polyphenols in sweet potato leaves were determined by HPLC. Antioxidant activity of polyphenols from sweet potato leaves was evaluated by scavenging DPPH free radicals and FRAP method. The inhibition assays of polyphenols from sweet potato leaves on α-amylase and α-glucosidase were evaluated in vitro. The optimal extraction condition was determined to be as follows: volume fraction of ethanol 88%， temperature 57 ℃， solid-liquid ratio 1 ∶ 20， extraction time 30 min. The extraction efficiency of polyphenols in sweet potato leaves was (15.34 ± 0.19) mg GAE/g. The main polyphenols of sweet potato leaves were 5-caffeoylquinic acid， 3-caffeoylquinic acid， 4-caffeoylquinic acid， 3，4-caffeoylquinic acid， 3，5-caffeoylquinic acid， 4，5-caffeoylquinic acid and 3，4，5-caffeoylquinic acid. The results of antioxidant activity and in vitro anti-diabetic assays showed that the polyphenols from sweet potato leaves had substantial effect on antioxidant and anti-diabetic activity. The DPPH free radical scavenging capacity and FRAP total antioxidant capacity were 11.57 mg TE/g and 12.30 mg TE/g， respectively. The inhibitory activities of polyphenols from sweet potato leaves towards α-amylase and α-glucosidase were 89.94% and 22.28%， respectively.