New Zealand A won the toss and opted to bat, reaching 308-3 in 79 overs before declaring.
Twenty-one-year-old Rachin Ravindra scored 112, while Henry Nicholls showed the selectors that he is well over his recent injuries with 76.
Chemar Holder, Alzarri Joseph and Raymon Reifer shared the wickets for the WI.
In their reply the WI lost John Campbell with just four runs on the board as the Jamaican continues to struggle with the bat.
Kraigg Brathwaite is not out on 2 having faced 29 balls while Darren Bravo is not out on 8.