In order to study the mechanical behavior and constitutive model of 5083P-0 aluminum alloy at high strain rate， the RPL100 material testing machine and the split Hopkinson pressure bar （SHPB） were used for quasi-static experiments and impact dynamic compression experiments with strain rates ranging from 950 to 3 000 s^-1.The results show that with the increase of strain rate during compression， the yield strength， strength limit and flow stress of 5083P-0 aluminum alloy increase， and the strain hardening rate decreases. It has strain strengthening effect， obvious positive strain rate effect and thermal softening effect. The plastic deformation mechanism of the material is analyzed， it is found that the sliding system leads to large plastic deformation of the material. At the same time， due to the adiabatic temperature rise， the material shows the competition between strain hardening and thermal softening. Based on the Johnson-Cook model， the variability term is improved， and the adiabatic temperature rise is introduced. The improved Johnson-Cook model can better describe the strain rate effect of the material and accurately predict its flow stress. Finally， the new strain rate is used to supplement the experiment， and the rationality of the model is verified by comparison.