South Africa chose to bat first after winning the toss and scored a formidable 209/5 in their 20 overs.
After South Africa lost Hashim Alma early on, opener Quinton de Kock (45) continued his impressive show with the bat and added 65 for the second wicket with captain Faf du Plessis.
Ab de Villiers was first dropped by Samiullah Shenwari on 26 off his own bowling and then again on 35 by the same fielder at midwicket off leg-spinner Rashid Khan.
Rashid suffered most from De Villiers’s onslaught as the batsman plundered 29 runs in the 17th over with four sixes and a boundary to race past his fifty in 24 deliveries.
De Villiers added 76 for the fourth wicket with left-hander JP Duminy (29 not out), who guided South Africa past the 200-run mark with David Miller (19).
The Afghans made a great start with Mohammad Shahzad leading the charge with 44 off 19 balls.
Shahzad, who hit five sixes and three fours, tore into paceman Kyle Abbott in the second over and took 22 runs off him.
The right-hander took Afghanistan to 47-0 in three overs, before paceman Chris Morris uprooted his stumps.
At halfway stage, Afghanistan were ahead of South Africa’s score on 103 for two but later lost too many wickets to keep up with the required run rate. Afghanistan were all out for 172.
Chris Morris took four wickets that earned him the player of the match award, while leg-spinner Imran Tahir and fast bowlers Abbott and Kagiso Rabada all picked up two wickets each.
Afghanistan, who also lost their opening match against defending champions Sri Lanka, have little chance to advance past the Super 10 stage after their second loss.
