Ruth Davidson wants graduates to pay back £6,000 towards their education once they are earning more than £20,000 a year.
She said the money would be put towards post-16 education, and replacing the cash she said had been "ripped out" of the bursary system by the SNP.
Scotland's other three main parties are committed to free university tuition.
Speaking on the BBC's Good Morning Scotland programme ahead of the Holyrood election on 5 May, Ms Davidson said it was "shocking" that children from poorer backgrounds were half as likely to go to university in Scotland than England, where students pay tuition fees of up to £9,000.
She said: "What we want to introduce is a scheme by which, once you have graduated and once you have a degree, once you are in a job earning over a certain amount of money, over £20,000, you start to pay back a contribution to the education that you received.
"It would be phased in so it would be only new graduates. We wouldn't backdate it to anybody.
"On average, people with a degree earn £100,000 more over their lifetime that those people who don't have one.
"If you continue in low-paid employment then you don't have to pay this back. That is why it is a graduate contribution."
University tuition fees were initially limited to £1,000 when they were introduced in England in 1998, but now stand at up to £9,000.
Ms Davidson said her party's plan for a charge in Scotland would be capped at £1,500 for every year of a graduate's degree for the full term of the next parliament.
She added: "We have universities in Scotland that are crying out for more funding. We have a college sector which has been slashed and burned by the SNP in order to fund this shibboleth of free education.
"We have European students coming here who don't have to pay a penny for the degree that they receive and this would be a way for them to contribute too."
And she insisted that higher education in Scotland was not truly free as it had "cost us 152,000 college places", put barriers in the way of the poorer people who want to go to university and put "a cap on the number of Scottish students that are actually able to go".
During the interview, Ms Davidson also said she would fight to ensure there was not another independence referendum.
And she explained her party's plans to bring back prescription charges in Scotland, which she said had cost £60m to the NHS in Scotland.
She said there would be a charge of £8.40 for prescriptions, although people on low incomes, students, pensioners, patients with long-term conditions and pregnant women would not have to pay.
Ms Davidson said it was not fair that people earning "good salaries" should cost the NHS money by getting their prescriptions for free.
She added: "I am prepared to pay a contribution if that means someone else doesn't have to wait an hour for a bedpan in a hospital ward or can get a cancer drug that is otherwise being denied them."
The SNP government scrapped prescription charges in Scotland five years ago - leaving England as the only part of the UK to charge for them.
Responding to Ms Davidson's interview, Scottish Labour's Jackie Baillie said the Conservative leader was "against asking the richest 1% to pay a bit more to stop the cuts, but she does want to impose hidden taxes on students and on the sick."
In the televised STV leaders' debate on Tuesday, SNP leader Nicola Sturgeon claimed the Conservatives were "not the party of low taxes" but the "party of hidden taxes".
And Liberal Democrat leader Willie Rennie said Ms Davidson "really only wants to cut taxes for the rich - she doesn't want to improve services for anybody else".
The Scottish Conservative leader has defended her party's plans to end free university tuition in Scotland.