Salhadin Bargecho scored an own goal off a corner on 23 minutes to put Sudan in the lead. Yusuf Yasin thought he had pulled his side level three minutes later but his goal was overruled for an offside.
Ibrahim Salah stretched Sudan's advantage with a delicate lob over the advancing Dereje Alemu in the Ethiopian goal on 69th minute to bury the hopes of the Ethiopians for any comeback as the scores stood at 2-0.
Salah raised his goal tally to four goals becoming the top scorer in the tournament.
Ethiopia's effort to fight back and get an equaliser were thwarted by a robust and steady Sudan defence which remained steadfast.
The win for Sudan ensured they set up a mouth watering semi final clash with Zambia on Tuesday as they seek the final berth.