Animal Rising activists plan to scale fences and enter the track at Aintree Racecourse before the start of the Grand National race, the group said.
The climate and animal rights group said up to 300 activists will participate in the race from 9.30am on Saturday, where they plan to prevent the race from starting.
They will also block traffic by running a slow march along Ormskirk Road, the main access route.
Nathan McGovern, a spokesman, said: “We plan to periodically block Ormskirk Road, the approach road to the front of the racecourse, to disrupt entry to the venue during the day.
“The group of people in front will peacefully attempt to make their way through the perimeter fences/walls at the front of Aintree prior to the start of the Grand National race with the intention of making their way towards the track.
“And all this before the race even started. We will not enter the track if there are horses and jockeys on horseback”.
Merseyside Police said they have a “robust policing plan in place” and are working with Aintree’s owners, the Jockey Club, in preparation for any incidents.
One horse has already died at the Grand National Festival – Envoye Special, ridden by James King – after going down in fox hunting just after 4pm on Thursday.
It is the 60th horse to have died at Aintree in the last 23 years.
Animal Rising, which changed its name from Animal Rebellion on Monday to move away from the Extinction Rebellion umbrella, wants to use the biggest event on the UK horse racing calendar to highlight the ‘broken relationship’ between humans and animals.
Mr McGovern said: ‘It’s a spotlight that we really need to use to propel a national conversation about our broken relationship, not just with horses but with all the animals we use, whether it’s for food, recreation, entertainment and dog and racehorse.
“It’s largely a bigger picture of acknowledging that, in a nation of animal lovers, we’re not really meeting those values with our actions.”
Animal Rising’s plans for the Grand National first became public when an undercover reporter from the Mail on Sunday attended a meeting earlier this month.
They said the activists planned to use ladders and bolt cutters to cross Aintree’s perimeter fence.
A Merseyside Police spokesman said: “Merseyside Police have a robust policing plan in place for Aintree, as with any major public event, to ensure the safety and well-being of all involved.
“We have been working with our partners, including The Jockey Club, over a number of months in the lead up to this year’s festival to ensure that all necessary plans and processes are in place to deal with any incidents that may arise and to prevent any significant or continuing disruption to tender participants, local residents and businesses.
“We respect the right to peaceful protest and expression of opinion, but public order or criminal offenses will not be tolerated and will be dealt with firmly.”
A spokesperson for Aintree Racecourse said: “We respect the right to peaceful protest but sincerely hope that Animal Rising will reflect on the legitimacy and accountability of the proposed actions.
“Their actions could endanger the horses they claim to protect, as well as jockeys, officials and themselves.
“As you would expect, we are working closely with Merseyside Police to ensure the safety and enjoyment of everyone is protected, including all participants, human or equine, at the Grand National.”
A spokesperson for the British Horseracing Authority added: “While we respect everyone’s right to protest safely and lawfully, we condemn any unlawful action, especially if it puts the safety of any horse, jockey, official or supporter at risk.”