Skipper Dane Van Niekerk won the toss in Canberra and opted to bat, with her team building 195 for three, anchored by powerful opener Lizelle Lee’s 101.
It was the biggest score in the tournament’s history, beating India’s 194 for five against New Zealand in Providence in 2018.
In reply, Thailand were all out for 82 with South Africa bagging a hat-trick off Shabnim Ismail’s bowling, although one was a run-out.
“The box we wanted to tick today was to take the win,” said Van Niekerk. “Credit to Lizelle for that century… but I think our fielding let us down a little bit today.
“I don’t think we were at our 100 percent best today.”
The Proteas registered a commanding victory over England in their opening game and by thrashing Thailand, have two wins from two to be well-placed in Group A.
England, who got their campaign back on track with a dominant victory over Thailand, play Pakistan later Friday. The West Indies, also with two wins from two, are in action on Sunday.
In front of a sparse crowd at Manuka Oval, Thailand got an early breakthrough with Van Niekerk chipping a Ratanaporn Padunglerd delivery to midwicket for an easy catch.
But Lee got the scoreboard moving with a flurry of boundaries an she built a big partnership with Sune Luus, bringing up her half-century with a huge six down the ground.
In a bid to keep South Africa guessing, Thailand used seven different bowlers in the opening nine overs. But the tactic backfired with too many loose deliveries.
Lee raced to her maiden T20 century, in her 72nd international, off 59 balls, with three sixes and 16 fours, before being caught and bowled by Suleeporn Laomi on the very next delivery.
Luus (61 not out) and Chloe Tryon (24) hit out late on to ensure Thailand faced a huge target.
The Thais survived two early dropped catches before Ismail stepped up for an incredible fourth over.
Nattaya Boochatham was run out off the first delivery, then Ismail cleaned-bowled both Nannapat Khoncharoenkai and Naruemol Chaiwai from the next two to leave Thailand reeling at 15 for three.
Onnicha Kamchomphu made a spirited 26, including her team’s first six of the tournament, but that was as good as it got for the Thais.
“All credit to Lizelle, she hit the ball hard but we also didn’t get our lines and lengths right,” said Thai skipper Sornnarin Tippoch. “That’s something to improve on, also our fielding today.”
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