Aimed　at　the　selective　catalytic　reduction　(SCR)　system,　an　electronic　control　unit　(DCU)　was　developed　under　V-type　procedure.　Development　of　DCU　software　and　hardware　were　carried　out　simultaneously,　shortening　largely　the　development　cycle.　The　self-developed　DCU,　integrated　with　Bosch　SCR　system,　has　a　high　NOx　conversion　efficiency　without　ammonia　leakage,　reaching　almost　90%　at　mid　and　high　engine　load.