An asphalt antistripping agent without amines was prepared with phosphoric hydroxyl organic compounds as the main component and its performance was evaluated by water boiling method,heat-ageing and thermalgravimetry.The results show that the optimal formula of the antistripping agent is:w(LOP)=15%,w(SP)= 5%,which could improve the adhesion between asphalt and acidic stones greatly.It can increase the adhesion grade from 1~3 to 5 and keep good effect even after heat-ageing.Meanwhile,the functionary mechanism was preliminarily discussed by using FTIR spectroscopy and leaching experiment with monododecyl phosphate and silica H as the representation.It is shown that the adsorption of monododecyl phosphate on the surface of silica H is chemical adsorption and according with Langmuir adsorption isotherm formula.