The work aims to establish and optimize a method for the determination of fluorine in disposable food-contact bio-based plastics (hereinafter referred to as bio-based plastics) by oxygen bomb combustion-ion chromatography, and analyze the fluorine content of commercially available bio-based plastic products. The oxidative decomposition of bio-based plastics occurred at high temperature by oxygen bomb combustion, and the fluoride was converted into free fluoride ions, which were absorbed or dissolved in the absorbent solution, and then eluted with 5.0 mmol/L sodium bicarbonate and 1.0 mmol/L anhydrous sodium carbonate solution as the mobile phases, with an injection volume of 20 μL and a flow rate of 0.8 mL/min. The determination was carried out on a Metrosep A Supp 7 column (250 mm×4.0 mm, 5.0 μm) and Metrosep A Supp 5 Guard column (50 mm×4.0 mm, 5.0 μm) at a column temperature of 45 ℃ with a conductivity detector, and was quantified by external standard method. The correlation coefficient for the determination of fluorine content in bio-based plastics by oxygen bomb combustion-ion chromatography R2 >0.995, the limit of detection (LOD) was 5.0 mg/kg, and the limit of quantification (LOQ) was 10 mg/kg, with good linearity, the spiked recoveries were in the range of 93.8%-98.4%, and the precision ranged from 2.9 to 6.8% (n=6). By quantitatively analyzing the fluorine content in 119 actual samples, the overall detection rate was 94.11%, and the overall failure rate was 15.94%. The detection rate in PLA straws, PLA+PBAT straws and PLA+PBS straws was 100%, and the failure rate was 45.16%, 30.77% and 5.88%, respectively. The method is reliable, convenient, sensitive, with good separation effect, and suitable for the determination of fluorine content in bio-based plastics.