The dynamic compression strength of concrete which undergone cyclic loading and subjected to water pressure was carried out, and effect of water pressure and cyclic times on strength of concrete was analyzed. Strain rates of tests were 10^-5/s, 10^-4/s, 10^-3/s and 10^-2/s, and water pressure ranged from 0 to 10 MPa. The results showed that strength of saturated concrete under different water pressure increased with the increasing strain rate, and that also increased with the increasing water pressure. Under the same water pressure, the concrete strength increased more significantly when the strain rate was higher. After cyclic loading, strength of saturated concrete showed the phenomenon of the first increase and then decreased as the number of load cycles increased. The higher the strain rate, the greater number of load cycles with maximum concrete strength. The relationships between concrete strength and strain rate, water pressure were established, which was in good agreement with the experimental data. Furthermore, the pipe pore model was introduced, and the mechanism of pore water on the concrete strength was explained and based on the principle of mercury intrusion porosimetry and pore distribution.