The match was played in wet conditions in front of 15 000-red clad home fans at the Malabo Stadium on Sunday.
The hosts took the lead in the 38th minute when striker Gloria Chinasa rose high in the penalty area to collect a cross from the right and head home, wide of a diving SA goalkeeper Thoko Mndaweni.
Midfielder Refiloe Jane played her heart out in tackling and winning possession in a bid to supply opportunities to strikers Portia Modise and Andisiwe Mgcoyi.
The match was marred by University of Johannesburg (Sasol League Gauteng) star Noko Matlou being fouled early in the second half and taken to hospital with a suspected neck injury.
Matlou was replaced by Cape Town Roses (Sasol League Western Cape) attacker Jermaine Seoposenwe, who had few opportunities on the ball in the wet conditions.
Banyana will face Senegal in Malabo on October 31, and will leave the island and travel to Bata for their final group encounter with DR Congo on November 3.