The reinforced concrete beam-column joint exhibits different properties under dynamic loading when compared with that under quasi-static loading, due to the effect of strain rate. However, the majority of previous studies are focused more on the rate effect of concrete and reinforcement, but less on beam-column joints. Based on the former considerations, the seismic behavior of 15 cruciform specimens subjected to various strain rates is studied in this paper, aimed at attaining a better understanding of the effect of strain rates on beam-column joints. In terms of the effect of different strain rates, the failure mode, carrying capacity, stiffness degradation, and energy dissipation of beam-column joints are discussed in detail. An empirical equation to predict the dynamic increase factor of horizontal shear carrying capacity of beam-column joints under different axial compression ratios and strain rates is also proposed through multiple linear regression analysis. Finally, four adjustments for the softened strut-and-tie model are made to get better predicting of the test results. It has been proved that predicted results by the improved softened strut-and-tie model are in good agreement with the test results.