Abstract: In order to study the ultrasonic prediction method of damage and failure of early age roadside filling concrete,four early age filling concrete specimens of 7,14,21,28 d were prepared. The microstructure was observed by scanning electron microscope,and the uniaxial compression mechanical properties were tested. The variation of continuous ultrasonic parameters in the process of damage accumulation of filling concrete was analyzed. The experimental results showed that with the increase of age,the internal structure of the filled concrete specimen was gradually dense,leading to nonlinear increase in the uniaxial compressive strength and the elastic modulus of the concrete. The Poisson's ratio showed a nonlinear decreasing trend,and the ultrasonic wave velocity and the main frequency amplitude showed an increasing relationship. The amplitude of the main frequency had a high correlation with the crack propagation of the specimen. According to the extreme value point of the main frequency amplitude,the crack closure stress point σ'_cc and the damage stress point σ'_cd were determined. The crack development was divided into three stages according to the characteristic stress point. The maximum value point of the main frequency amplitude can be used as the precursor information of the instability and failure of the filling concrete,which provided a theoretical basis for the ultrasonic prediction of the bearing performance of the roadside filling concrete.