Abstract： Objective To evaluate the adhesion,proliferation,alkaline phosphatase (ALP) activity and the expression of osteogenesis-related genes and osteoprotegerin (OPG)/receptor activator of NF-κB ligand (RANKL) of osteoblast-like cells on a type of near β-type titanium alloys (Ti-5Zr-3Sn-5Mo-15Nb,TLM) surfaces modified by the double glow plasma nitriding technology,and to investigate the effect of the modified surfaces on the initial functions of osteoblast-like cells.Methods The surfaces of TLM were modified by the double glow plasma nitriding technology.TLM surfaces without modification were used as control.Cell morphology was observed with scanning electron microscopy (SEM).Methyl thiazolyl tetrazolium (MTT) method was used to measure cell proliferation.Cell ALP activity was evaluated by using reagent kits.The mRNA expression of Runt-related transcription factor-2 (RUNX2),type Ⅰ collagen alpha 1 chain (COL Ⅰ o1) and OPG/RANKL were examined by quantitative real-time PCR(qRT-PCR).Results Four hour following cell alture,cells on modified surfaces extend filopodia and intercellular junction was tight.Three days later,cell proliferation (0.277±0.007) was significantly higher than that in control group (0.249 ± 0.004) (P＜0.01).After two weeks,ALP activity on TLM modified layer (173.6 ± 1.89) was significantly higher than that on unmodified TLM (162.6±2.4) (P＜0.01).The mRNA expression of osteoblast marker RUNX2,COL Ⅰ α1 were stronger than that in control group (P＜0.05).The expression of OPG mRNA was higher than that in control group (P＜0.01),and RANKL mRNA expression was significantly lower than that in control group (P＜0.05).Conclusions The TLM surface modified by the double glow plasma nitriding technology has a positive effect on osteoblasts initial adhesion,proliferation and differentiation,and it can also improve expression of OPG mRNA and has an inhibitory effect on RANKL mRNA expression of osteoblasts.