The former Wimbledon and Swindon Town centre-half has been brought in by Carla Ward following the departure of Charlie Baxter from the position.
Reeves most recently spent a five-year spell coaching AFC Wimbledon's Under-23s side and was instrumental in the development of several players who have been sold to Premier League clubs.
He was part of the Wimbledon coaching staff as they gained promotion to League One via the Play-Offs in 2016.
Reeves, 52, also has experience as assistant manager at both Brentford and Swindon.
From Birkenhead, he began his professional playing career at Norwich City before joining Chester City and then Rochdale, where he carved out a name for himself as a reliable and competitive defender.
He moved onto Wimbledon in the Premier League for four years.
Then it was to Swindon, where he made 246 appearances (16 goals) between 1998 - 2006.
Reeves twin brother, David, also played professionally, notably for Bolton Wanderers.
Head Coach Ward commented: "We're delighted to get Alan on board, he's someone I've known for some time and we have similar ideas with different qualities so for me it's the perfect fit.
"He comes with a wealth of experience and knowledge in the game and bringing that to both myself and the girls will only be positive for what we want to achieve."
The Club would like to thank Charlie for his time with us and we wish him the best for the future.