Objective:To study the effects of the modified sandblasting surface treatment on the bone implant interfacial shear strength of titanium dental implant.Methods:Titanium implants with smooth surface or modified sandblasted surface were inserted into femoral medialis condyli of dogs at random.The samples of implant with surrounding bone tissue were prepared in blockes and the shear strength of the interface was measured with Instron electronic pull out tester 2,4 and 12 weeks after operation. The modified sandblasted surface of the implant was observed with SEM and X ray spectroscopy 12 weeks after operation.Results:2 and 12 weeks after implantation the shear strength(MPa) between bone tissue and implants with modified sandblasted surface was 4.28?0.88 and 7.54?0.34 respectively,that between bone tissue and implants with smooth surface 0.09?0.08 and 1.43?0.46 respectively.SEM and X ray spectroscopy observation revealed that the most parts of the sandblasted surface of the implants were covered by bone tissue and bone matrix deposited into the pores created by the acid etching.Conclusion:The rough surface of titanium dental implant created by the modified sandblasting surface treatment can enhance the shear strength between bone tissue and implant.