SCR post-processing technology had more advantages than other technology which applied to Euro Ⅳ/Ⅴ diesel engine. In order to develop control strategy of SCR post-processing system, methods of experiment and simulation were employed. Firstly coordination control strategy was designed and tested in matlab based on the state machine theory, then raw emission model, NH3 target coverage rate estimation model and mass ratio calculation model of NH3 and NOx chemical reaction from SCR catalyst were calibrated by bench test, finally correction algorithm for heat hysteresis of catalyst substrate and NH3 leak control strategy in the transient operation condition were fulfilled, which improved the SCR control system robustness. The dosing control unit using above control strategy was adopted in the target engine, which made NOx conversion efficiency achieve 60 percent and average NH3 leak equal to 1×10 -5 . Emission NOx value of ESC and ETC was 3.01g/(kW·h)和3.15g/(kW·h), which validated the heavy duty diesel engine can satisfy Euro Ⅳ emissions regulations.