Last year’s picnic in the grounds of the 19th century mansion attracted more than 250 vehicles and 1500 visitors. Similar numbers are expected this year.
The day will also include a Dakota flypast, courtesy of the Battle of Britain Memorial Flight, subject to the weather.
Bletchley Park is the historic site of British codebreaking activities during the Second World War and the birthplace of modern computing.
Today the museum tells the story of the codebreakers and is home to the largest collection of Enigma machines on public display anywhere in the world.
Also on display is the Lorenz machine, an even more complex cipher system used by Hitler and his high command. Visitors can also see the rebuilt working bombe machine and a wide range of exhibitions which tell the Bletchley Park story.
Exhibitors will be given entry to the park at a discounted rate of £3 per motorbike, including riders and passengers.
Normal admission prices apply for other visitors. A guided tour is included in the admission price, which also allows visitors to return as many times as they like for a whole year. More information on www.bletchleypark.org.uk