Abstract: 【Objective】 This project aims to identify the evolutionary relationship of two newly discovered porcine reproductive and respiratory syndrome virus strains HNHK1-2021 and HNLG1-2021 in Hainan,China. 【Methods】 The ORF5 gene was amplified and sequenced by PCR method. Multiple sequence alignment was performed using MegAlign software, and phylogenetic tree was constructed using MEGA X software neighbor joining method. 【Results】 The nucleotide similarity of PRRSV HNHK1-2021 and HNLG1-2021 strains was 82.9%, and the deduced amino acid similarity was 82.6%. HNHK1-2021 strain and NADC30-like PRRSV, QYYZ-like PRRSV, VR2332-like PRRSV and JXA1-like PRRSV sequence alignment: 80.8%-82.8%, 90.2%-92.0%, 82.1%-83.4%, 81.9%-84.4%,deducing the amino acid similarity was 82.1%-84.6%, 91.5%-94.5%, 80.1%-83.1%, 82.6%-84.6%; HNLG1-2021 strain and NADC30 PRRSV, QYYZ PRRSV, VR2332 PRRSV and JXA1 PRRSV sequence alignment, the nucleotide similarity of which was 83.7%-84.6%、81.8%-83.6%, 97.7%-99.5%, 85.6%-90.4%, the deduced amino acid similarity was 83.6%-85.1%, 81.1%-82.6%, 96%-98.5%, 86.1%-90.5%. 【Conclusion】 The two virus strains belong to the North American type PRRSV, and the HNHK1-2021 strain belongs to the QYYZ class PRRSV (lineage 3). The HNLG1-2021 strain belongs to the VR-2332 class of PRRSVs (lineage 5).