Police used tear gas and batons to disperse students demonstrating against a ban on a planned march to the presidential residence. They wanted to protest against a poll on 18 November which many opposition parties intend to boycott.
Closure of the campus follows two days of unrest in which 10 students were arrested and several people injured, including a British Airways crew.
"The University of Zambia has been closed because the atmosphere here is not conducive to academic work," the university senate said in a statement.
The announcement came as students armed with stones fought pitched battles with police and barricaded roads leading into the campus. Traffic on a nearby highway was stopped for part of the morning as students pelted motorists before being driven back by teargas and baton charges. The campus was later sealed off.
Student leaders said they wanted President Frederick Chiluba to reopen dialogue with his political opponents and possibly suspend polls until all political parties reached consensus on the rules governing the elections. "Today's riot was caused by an unwarranted attempt by police to disrupt a peaceful demonstration by students," a student leader said.
Seven opposition parties, including former president Kenneth Kaunda's United National Independence Party (UNIP) are boycotting the polls, which they say have been arranged to ensure that the ruling Movement for Multi- party Democracy (MMD) remains in power.
The parties are opposed to a new constitution which bans some candidates, including Mr Kaunda, from contesting the presidential race on the grounds that they are not native-born Zambians. Mr Kaunda was the country's head of state for nearly three decades, leading Zambia to independence and ruling until Mr Chiluba defeated him in polls in 1991.
Opposition parties are also unhappy with the voters' register, which omits 2.3 million of the 4.6 million eligible voters, and with the state- owned media's coverage of campaign, which they say favours the ruling party.