In this study, deep eutectic solvents were used for the extraction of flavonoids from Spatholobus suberectus. The extraction effect was measured using UV spectrophotometer and found that the deep eutectic solvent consisting of choline chloride and triethylene glycol (1:2) was the best extraction. The solvent water content (%), liquid-to-material ratio (v/m), and extraction temperature (K) were optimized using the central composite bounded design response surface method in a single-factor experiment. The results showed that the extraction yield of chickweed flavonoids reached 96.01 (mg/g) at a liquid-to-material ratio of 39:1, a water content of 43% in DESs and an extraction temperature of 336.6 K for 5 min, which was 2.85 and 4.12 times higher than that of the control group (90 min extraction) using 60% ethanol and water, respectively. The antioxidant activity of the extracts was evaluated using 2,2-Diphenyl-1-(2,4,6-trinitrophenyl)hydrazin-1-yl (DPPH) and it was found that the extracts inhibited DPPH by 89.765%, indicating the high content of flavonoids extracted. This study provides an idea for the extraction of functional components of biological origin.