The surface quality of material significantly affects the accurate measurement of the ultrasonic attenuation coefficient. According to the influence of surface roughness on the propagation of a vertical incident ultrasonic beam, a method of contact ultrasonic-attenuation coefficient correction considering surface roughness was proposed. Firstly, based on the correction theory of reflection coefficient of rough interface in the case of uncoupling and the calculation formula of reflection coefficient of smooth interface in the case of coupling, the formula of reflection coefficient of rough interface in the case of coupling was derived. Then, a method of contact ultrasonic attenuation coefficient correction including roughness information based on the formula of attenuation coefficient was proposed. Finally, cylinder specimens of 45 steel and 304 stainless steel with different surface roughness were prepared, and the ultrasonic measurement platform of attenuation coefficient was established. The influence of surface roughness on signal time domain and frequency domain was investigated to verify the validity and practicability of the proposed correction method. Experimental results show that the proposed attenuation model can effectively compensate the attenuation of ultrasonic backscattered signal caused by roughness, and the relative measurement error of transmission method is less than 6%.