The X Factor finalist responded to the comedian's comments about his appearance over the weekend.
The argument began when Boyle tweeted: "James McArthur is like a cross between a tramp and a duckling #xfactor (sic)."
Arthur quickly responded, saying: "Poor old man making yet more s**t jokes about Xfactor because he knows that's the only way he can get attention any more #prat"
Boyle continued the spat, tweeting: "I think if I wanted attention I'd sing covers on a talent show, inked up like a schooldesk in a remedial class."
Arthur then wrote back: "Your about as funny as aids.
"Your a sad man and I can't wait to see you coz it's about time someone gave you a reality check."
Boyle recently won over £50,000 in libel damages from The Mirror.
Jurors awarded the comedian £50,400 for a defamation of him as racist, and an additional £4,250 for a claim that he was forced to quit panel show Mock the Week.
Boyle has caused controversy with his comments in the past, including jokes about the Paralympic Games back in August.
Arthur will compete against Christopher Maloney and Jahmene Douglas in the live X Factor finals on Saturday and Sunday (December 8 and 9).
Photo gallery - 'The X Factor' semi-final results show in pictures:
Copyright: Ken McKay/Thames/Rex Features