The Tongans struck first in the 6th minute with a counterattack that saw Mele Kafa power a shot into the back of the net.
PNG regrouped and equalised in the 20th after a perfect through ball from Ramona Padio that found the boot of Selina Unamba who did the rest.
Padio then gave PNG the lead right before the break slotting one past keeper Mele Akolo to make it 2-1.
PNG dominated the second half and scored two more times through Padio in the 51st and Nicollete Ageva in the 88th.
This morning’s victory made it two wins from three games for PNG.
PNG’s next match will be against Fiji this Friday at 3pm (1pm PNG time).