Wilson was suspended this week for an unspecified violation of team rules. He said in a press release Saturday that he has left the program because of the actions of first-year coach Mike Leach and his staff.
Wilson said the new staff has "preferred to belittle, intimidate and humiliate us." That included physical abuse, Wilson said.
Athletic director Bill Moos said in a statement that it was unfortunate Wilson quit.
"I believe I join many Cougars in wishing Marquess well in his future endeavors," Moos said. "We have procedures in place that were developed to monitor student-athlete welfare in all of our sports programs. 'We will continue to follow those procedures and modify them if needed."
Wilson, a junior, set school single-season records last year with 82 receptions and 1,388 yards receiving. This season, he leads the team with 52 receptions for 813 yards.