The sensing characteristics of surrounding refractive index (SRI) were investigated on the pretreated FBG(PFBG) by hydrofluoric acid (HF) etching treatment and the tilted fiber bragg grating (TFBG) with an angle of 4° through several experimentts. in which the SRI ranges from 1.40 to 1.45. the result demonstrated that the SRI sensing characteristic of TFBG was superior to that of PFBG. using width changed (∆L) of high-order modes of TFBG, we can detect SRI whose value ranges from 1.40 to 1.45, between which a good linearity of SRI sensing characteristic can be obtained, and the correlative coefficient can reach 99.543%. the features of TFBG may prossess prospects of application in biological and chemical fields.