Abstract: In order to rapidly separate Pa and further study Pa solution chemistry, the solvent extraction of protactinium from HCl medium by methylisobutyketone in benzene was investigated at different concentration of extractants and HCl. The effect of shaking time on the extraction of protactinium with 6 mol/L methylisobutyketone in benzene from 8mol/L HCl and mixed HCl-0.03mol/L HF solutions was also discussed on the basis of the experimental results. It can be concluded that extraction equilibrium can be reached within 10s, methylisobutyketone can almost quantitatively extract protactinium from 8mol/L HCl solution, at the same time, the presence of 0.03mol/L HF in HCl solutions seriously affect the extraction behavior of protactinium (Ⅴ).