Through the experiments on the improved pull-out tests of full-thread glass fiber reinforced plastic (GFRP) anchor bolts,the bonding behavior between the bolts and rock mass is studied. By studying the anchorage force of different GFRP anchor bolts,the parameters for application of GFRP anchor bolts to engineering practice are proposed. The testing results indicate that the anchorage force of the bolts increases with the increases of bolt diameter,anchorage length and mortar strength;the bonding strength of bolts increases with the increase of mortar strength,but decreases with the increases of bonding length and bolt diameter. And the results are explained with the bonding stress distribution of the GFRP anchor bolts. By the results,several conclusions are drawn:(1) the recommend diameter of the GFRP anchor bolts in engineering is 12-32 mm;(2) the anchorage length of the GFRP bolt should be larger than 20 times of its diameter;and (3) the compressive strength of the mortar used as anchor agent should be more than 15 MPa.