Andy Stewart, who is running in Doncaster North, said the vitriol he has experienced during the election campaign has been on "another level".
The candidate said that, as a mixed-race man, he has seen racism first-hand but told voters the abuse he has witnessed in the past month has been something entirely different.
"It does upset me, because people shouldn't be doing that at all," he said.
He added: "There's a new kind of racism about.
"It's not for colour, it's not for creed or race, and it's not for religion - it's for opinion. It's racism of opinion.
"You are then charged with being of this kind of opinion, and you're ostracised.
"People turn around and tell you that your opinion's not worth anything, you're charged with being different to other people."
He said fellow Brexit Party candidate Surjit Singh Duhre, who is standing in Doncaster Central, had also been subjected to abuse and branded a liar.
Speaking at the Earl of Doncaster Hotel, Mr Stewart told a group of activists that he had recently been lectured on racism by a white middle-class man.
He said: "I can tell you, with a black grandad walking down a predominantly white area, I know what it's like.
"I know what racism is like. But I don't know what this (the abuse) is like."
But Mr Stewart said that, despite the unpleasantness, he has "loved every minute" of the campaign, adding: "All we want to do is make Doncaster a better place."
In his own speech, Brexit Party leader Nigel Farage said the election campaign had been "pretty appalling" - both because of the abuse, and because of the policies of the other parties.
He later told the PA news agency: "For people in a free society to put themselves forward for public office is a right, that they deserve to exercise if they so choose.
"I think the hounding of people, saying 'Stand down, you shouldn't be here', I think that's been appalling.
"I just can't imagine that our politics has ever been in a worse place than it is now."
Mr Farage said he feels the abuse is a consequence of the first-past-the-post system, which he believes leads to "endless negativity".
He added that, after the election, he will write a book about the campaign, which will make the case for changing the electoral system.