Mr Key said President Park indicated she was receptive to an FTA with New Zealand when he met her prior to her election late last year.
"I think we'll just have to see how sympathetic she is now that she's president."
Mr Key has met President Park, the daughter of South Korea's former military ruler Park Chung-hee, twice before.
"I found her warm and engaging when I met her last time, and she's obviously a formidable political person and leader for Korea.
"She's well liked here and in the end, she's the person that calls the shots. So if we are going to get an FTA with Korea it will be because President Park makes it happen."
Mr Key even underlined the importance of an FTA when he spoke to veterans at New Zealand ambassador Patrick Rata's residence this morning following the wreath laying.
He pointed out New Zealand exporters to South Korea pay about $200 million a year in tariffs on $1.55 billion worth of goods while Korean imports only face tariffs of about $5 million on about $1.8 billion in goods.
Mr Key will meet President Park at the Blue House presidential palace at 5pm today New Zealand time.