In order to study the biological function of TrFQR1 in Trifolium repens cv. ‘Ladino’, we cloned cDNA sequence of TrFQR1 by RACEPCR and RTPCR and analyzed with bioinformatics software. The expression pattern of TrFQR1 was detected by realtime fluorescence quantitative PCR(RTqPCR). The results showed that: (1) TrFQR1 was obtained at a length of 1 003 bp, which open reading frame contained 612 bases and encoded 203 amino acid. The molecular weight was 21.88 kD and the isoelectric point was 5.96. TrFQR1 was a hydrophilic protein that highly conserved in evolution without signal peptide and transmembrane domains. The N terminal 11-15 aa and the C terminal 112-165 aa were the FMN binding sites. (2) RTqPCR results showed that TrFQR1 could respond to the all eight treatments. However, TrFQR1 presented different expression trends to those treatments. At 1.5 h after the treatment of 25 μmol/L SNP, 10 mmol/L H₂O₂ or 5 mmol/L CaCl₂ and 3h after the treatment of 15% PEG, the relative expression levels of TrFQR1 were upregulated significantly. The relative expression levels of TrFQR1 increased with the increase of treatment time under 200 mmol/L NaCl or 600 μmol/L CdSO₄. The relative expression of TrFQR1 gene were significantly decreased at 6 h after the treatment of 4 ℃ and 1.5 h after the treatment of 0.02 mmol/L NaHS.