Objective: To investigate the association of genetic polymorphisms in CYP2C9*3 with warfarin dosage in Li population patients with persistent atrial fibrillation (PAF) in Hainan Province. Methods: A total of 100 Li population patients diagnosed as PAF in our hospital were collected to research group. And 100 Han population patients diagnosed as PAF in the same hospital were collected to control group from January 2017 to December 2018. The indexes of serum warfarin levels, international normalized ratio (INR) standard time, warfarin average daily dosage and warfarin total dosage of two groups were recorded. The DNA samples of two groups were extracted. Then the SNP sites of CYP2C9*3 gene were genotyped by amplification refractory mutation system (ARMS-PCR) method. Results: Compared to control group, the genotype frequencies of A/A and A/C and the allele frequency of A in research group were lower (P<0.05), and the genotype frequencies of C/C and the allele frequency of C in research group were higher (P<0.05). The warfarin stable dosage and serum warfarin levels in two groups were different among three genotypes (P<0.05). The A/A genotype of warfarin stable dosage levels and serum warfarin levels was highest, and the A/C and C/C genotypes were no different (P>0.05). The A/A genotype of warfarin stable dosage levels and serum warfarin levels in research group was lower than in control group (P<0.05), but the A/C and C/C genotype of warfarin stable dosage levels and serum warfarin levels were no different between two groups (P>0.05). The INR standard time, warfarin average daily dosage and warfarin total dosage of Li population patients with PAF were different, and the sequence were A/A>C/C>A/C (P<0.05). Conclusion: The polymorphisms on CYP2C9*3 gene is related to warfarin stable dosage levels of Li population patients with PAF. And the INR standard time, warfarin average daily dosage and warfarin total dosage with C/C genotype of CYP2C9*3 gene are lower than those with A/A and A/C.