In order to study the error rate between calculated compressive strength and measured compressive strength of concrete members by ultrasonic-rebound combined method, concrete members of strength classes C20, C30 and C40 were designed and poured. The rebound value, ultrasonic wave velocity and compressive strength of three grades were tested under natural conditions with test age up to 730 d, and calculated compressive strength of concrete was estimated. The effect of age on rebound value, ultrasonic wave velocity, calculated compressive strength and measured compressive strength were compared and analyzed, and the relationships between rebound value, ultrasonic wave velocity and measured compressive strength of concrete members were linearly fitted according to test results. The results show that the development of rebound value of concrete members of three grades is similar to that of compressive strength. Ultrasonic wave velocity can be clearly divided into three stages with age, such as at long ages (after 180 d), the strength of concrete members with higher design grades (C40 and above) may be higher (within 10%) by using the ultrasonic-rebound combined method, and the strength of concrete members with lower design grades (C30 and below) may be lower (within 10%) by using the ultrasonic-rebound combined method. At long ages, ultrasonic wave velocity and rebound value are good at characterizing the compressive strength of concrete members from 10 to 70 MPa, and have high linear correlation with correlation coefficients of 0.95 and 0.93, respectively.