The protesters have said on social media that pro- independence politicians are expected to give talks at Barcelona University.
Jordi Vives, a spokesman for the students, told Catalan public television: "We are showing that as students we have a part to play and that for now we are staying put."
The remaining students were hold-outs from a group of about 2,000 that gathered in and around the university yesterday.
Several hundred occupied a central cloister near the offices of the dean and other university managers. Spain's Constitutional Court has suspended the October 1 vote while judges assess its legality.