The 18-year-old is yet to make a competitive senior outing for the club but has impressed with the Under-21 side.
Eddie Howe included the defender during the pre-season clashes with Valencia and Napoli and he came off bench against the Spanish outfit.
Harfield is keen to kick on from his taste of first-team action and hopes to remain in Howe's plans for the 2017-18 season.
"Pre-season has gone really well,” Harfield told Bournemouth's official website. "I've worked hard like a lot of the lads and I feel as though I'm playing well at the moment.
"Being involved against teams like Napoli and Valencia, teams I grew up watching and watch on TV now, is fantastic for me and the other young lads involved.
"I think I just need to keep pushing forward, keep knocking on the door and see where it takes me."