In this work, a partial element stage cut electrochemical hydrogen pump (EHP) model for multiple H2-contaning gases separation and hydrogen compression which embed real factors (anode impurity diffusion, hydrogen back-diffusion and anode catalyst deactivation) was established to study EHP performance accurately under full hydrogen concentration. The accuracy and reliability of proposed model were verified from four aspects (current density distribution, polarization curve, hydrogen recovery and purity) under different feedstock systems and wide pressure range. The model has good applicability and accuracy (R^2≥0.96, simulation and experiment results comparison). Simulation results show that high hydrogen back-diffusion ratio can cause low energy efficiency under high cathode pressure and low feedstock hydrogen content. The variation law of hydrogen purity under multi-operating conditions was studied, which shows dual-effect (PEM and GDL resistance) can affect hydrogen purity prominently through current density under low feedstock hydrogen content and applied potential.