An efficient procedure for ultrasound-assisted enzymatic extraction of crude polysaccharides from Trichosanthes Fructus (crude TFP) using response surface methodology (RSM) was developed. The Box-Behnken design was applied to optimize the effects of pH (X1), enzyme amount (X2), extraction temperature (X3), and liquid-to-solid ratio (X4) on the extraction. The statistical analysis indicated that the independent variables (X4, X2, and X3), the quadratic coefficients (X12, X22, X32, and X42), and the interaction coefficient (X1X3) had significant impact on the yield of crude TFP. The optimal conditions were determined as follows: pH 4.5, enzyme amount 5000 u/g, extraction temperature 45°C, and liquid-to-solid ratio 30 ml/g. The experimental yield of crude TFP was 6.58%, which was very close to the predicted yield of 6.71%. TFPI was then purified and characterized with Sephadex G-100 column, UV-Vis, GPC, and FT-IR. The average molecular weight of TFPI was calculated to be 1.49 × 105 Da. TFPI exhibited strong reducing power and possessed not only remarkable scavenging activities against ABTS•+ and DPPH radicals, but also high antitumor activities in C4-2, DU145, and PC3 cells. The results suggest that Trichosanthes Fructus and TFPI could be a novel potent natural medicine with antioxidant and antitumor activities.