In order to study the size effect behavior of recycled concrete under dynamic compression load, a meso‐scale model of recycled concrete was established. The particle size of coarse aggregate, replacement ratio of recycled coarse aggregate, and section size were used as parameters to explore the mechanical properties of recycled concrete under uniaxial dynamic compression load, such as failure mode, compressive strength, peak strain, and residual strength. The effects of strain rate, particle size of recycled coarse aggregate, and replacement rate of recycled coarse aggregate on the size effect of dynamic compression of recycled concrete were further analyzed. The results showed that under uniaxial dynamic compression load, the damage degree of recycled concrete deep and along with the change of the strain rate change, recycled concrete dynamic compression strength and strain rate were positively correlated. There is the critical strain rate is 1/s, which weaken the influence of the size effect, when the strain rate reaches 10/s, the dynamic compressive strength of recycled concrete increases with the increase of section size. At the same time, when the strain rate is high, the particle size of recycled coarse aggregate and the replacement rate of recycled coarse aggregate have little effect on the size effect behavior of recycled concrete.