Based on the linear elastic theory and one dimension stress wave assumptions, the spalling tests for C75 concrete bars were conducted by using a large diameter 74mm Hopkinson bar to study its dynamic tensile strength and strain rate effect. Firstly, the multipoint gauge mounting method was adopted to determine to dynamic elasticity modulus of concrete under different velocities of projectile. Secondly, the dispersion phenomenon of stress wave was greatly decreased via optimizing the projectile size. Finally, a new procedure for determining the coefficient of attenuation of concrete was further proposed, which could eliminate the influences of the nonuniformity of specimen, the differences of strain gauges and the attenuation weakness of signal. Experimental results show the dynamic tensile strength and strain rate are almost linearly correlated when strain rate ranges from 100 s-1 to 102s-1.