Thousands of visitors are expected to descend on the Bull and Butcher Field for the fun Bank Holiday event, with the donkey racing just one of the things to keep everyone entertained.
There will also be a fun fair, charity stalls and much more.
The event, which is now in its 47th year, raises money for about a dozen charities.
Organiser Dave Robinson said: "It's a great way to spend a bank holiday.
"It's a great community event with lots of fun for all ages and the money goes to good causes."
The gates open at 11.30am and Sandhurst Town Mayor Cllr Michael Brossard will officially open the event at noon. The first race takes place at 12.40pm.