Before concrete structures are subjected to dynamic loadings such as earthquake, usually they have already withstood static loads. Accordingly, the study on the strain-rate sensitivity of concrete should also be closely related to the initial static loads that concrete structures experience. But majority of the available documents concerning the dynamic properties of concrete do not take initial static load into consideration. In this study, experiments were carried out to investigate the effect of initial static load on the dynamic strength and deformation characteristics of concrete in compression. A load was initially applied on the specimen at a very low speed to a specified value and then the dynamic load was applied at a high strain rate up to the failure of the specimen. From the test results it was revealed that the initial static load had significant influence on the dynamic strength. The dynamic strength tended to decrease as initial static load increased. An exponential function was proposed to formulate the relationship between the initial static load and the dynamic strength.