<p>Fiber-reinforced concrete demonstrates effective synergy with surrounding rock masses through composite structural formation and load-bearing capacity, exhibiting significant potential in rock-burst hazard prevention. This study systematically investigates the influence mechanisms of strain rate variations, lithological differences and joint roughness coefficients (JRC) on dynamic compressive behavior and failure characteristics of rock-concrete composites through controlled impact tests with strain rates ranging from 74.0 to 122.2 s⁻¹. The results reveal that the dynamic compressive strength, dissipated energy, and dynamic compressive strength increase factor (DCSIF) of all composite specimens exhibit significant strain rate effects. Furthermore, the DCSIF and energy dissipation of the hard rock combined body demonstrate greater sensitivity to JRC variations ranging between 4 and 20, showing maximum increases of 68.60% and 97.69%, respectively. In addition, a dynamic constitutive model for the rock-concrete combined body is established based on elastoplasticity theory, incorporating the combined effects of JRC, strain rate and rock type. Experimental validation confirms that the model predictions align well with the observed dynamic compressive strength evolution, demonstrating its applicability for predicting compressive properties of rock-concrete combined bodies across various strain rate levels.</p>