Captain Sophie Devine has led the White Ferns to a comprehensive five-wicket win over South Africa at Seddon Park on Thursday.
Devine blasted 61 from just 41 balls to give her side a 2-0 lead in the five-game series, as the teams warm-up for the World Cup in Australia later this month.
Bowler Lea Tahuhu was the star with the ball for the hosts, taking two wickets for only 10 runs to restrict South Africa for 119 all out with two balls remaining in their innings.
Devine then stepped up to guide a well constructed NZ chase, getting her team across the line with 10 balls to spare.
The next T20 takes place at Wellington's Basin reserve on Sunday.
South Africa 119 all out in 19.4 overs (M du Preez 40; L Tahuhu 2-10) lost to New Zealand 121-5 off 18.2 overs (S Devine 61; A Khaka 2-24) by five wickets.