"We reject cosmetic elections and schemes against our demands for reform," read a banner carried by the demonstrators in Jabal Hussein, close to central Amman.
"The people want to warn the regime, the people want to reform the regime. (King) Abdullah, Jordanians are burning themselves and the regime does not care," they chanted.
More than 1,500 candidates, including 213 women, have been registered for the January 23 election, which the opposition Islamic party and other groups have boycotted over a lack of reform.
"The rule of the people is coming. Demonstrate and demand reform. The people will continue to demand regime reforms until the regime realizes that there is no room for procrastination," Hammam Said, leader of the Muslim Brotherhood, told the demonstrators.
The Brotherhood, the main opposition movement, has said it would boycott the election in protest at constituency boundaries it says are unfair, and at the failure to move towards a constitutional monarchy with an elected prime minister, rather than one named by the king.
"I am taking in this sit-in today to reject the election and Jordan's political reality, which is tearing apart our society," Fayza Abu Fares, a university professor, told Agence France Presse.
"The coming election will do nothing to change our reality," she said.