Abstract: Objective To investigate the susceptibilities of linezolid-resistant Gram-positive cocci to tedizolid, a novel oxazolidinoneantibiotic, and the drug resistance mechanism of tedizolid-resist ant isolates. Methods A total of 170 clinical isolates of non-repetitive Gram-positive cocei were collected ，including 46 linezolid-resistant Staphylococcus capitis ( LRSC), 19 linezolid-susceptible Staphylococcus capitis ( LSSC) , 55 linezolid-resistant Enterococcus ( LRE)，12 linezolid-susceptible Enterococcus ( LSE)，19 methicillin-resistant Staphyloccus aureus ( MRSA), 18 methicillin-susceptible Staphyloccus aureus ( MSSA) and 1 linezolid-resistant Staphylococcus aureus (LRSA). The minimal inhibitory concentrations ( MIC) of all isolates against tedizolid and linezolid were determined by the broth dilution method，and the antibacterial activities of the two drugs were compared. The resistance genes ofr and optrA and the mutation of 23S RNA V region in the tedizolid-resistant Gram-positive cocci were detected by PCR combined with Sanger sequencing. Results The MIC of tedizolid against LRSC ( MICgo> 256 μg/mL) was 4-32 μg/mL. The sensitivity rate and MIC of tedizolid against LRE ( MIC for linezolid: 4-16 μg/mL) were 10.9% and 0. 5-2 μg/ mL, respectively. One strain of LRSA was sensitive to tedizolid,and its MIC was 0.5 μg/mL. The MICs of tedizolid against LSE and LSSC were 0.5 μg/mL and 0.125 μg/mL, respectively. Analysis of resistance genes showed that the carrying rate of cfr gene in tedizolid-resistant Staphylococcus capitis was 87.0% ( 40/46)，and that the mutation rate of G2576T in 23S rRNA V region was 100%. The carrying rate of optrA gene in tedizolid-resistant Enterococci was 85.7% (42/49) ，which was signifcantly higher than that in tedizolid-susceptible strains ( 22.2%, P<0.001 ). One linezolid-resistant and tedizolid-susceptible Staphylococcus aureus stain carried the cfr gene. Conclusion The antibacterial activity of tedizolid against linezolid-resistant Gram-positive cocci is 8-32 times that of linezolid, and its resistance mechanism may be related to canying optrAgene and G2576T mutation in 23S rRNA V region.