Coming as hundreds of college staff face redundancy, the figures expose the sector to ridicule, the union claims.
The Association of Colleges says pay rates reflect the need for colleges to recruit the best
Between 2001-2 and 2008-9, the mean average pay of further education college principals increased from £76,506 to £119,482 or 56%, according to figures from the Learning and Skills Council which used to fund colleges.
'Huge pressure'
Over the same period, teachers' pay rose from £27,615 to £34,090, a rise of 23.4%.
In the last year, 2008-9, college heads had average pay rises of 7.1%. This compared with a 1% pay rise for teaching staff, according to the figures.
UCU general secretary Sally Hunt said she was not against people being properly rewarded for working hard.
"However, we believe colleges need to be up-front about why principals are enjoying such bumper pay rises compared to teaching staff.
"At a time when the public sector is facing huge pressure to show restraint these large rises in principals' pay are embarrassing the further education sector."
Complex organisations'
Employment director at the Association of Colleges (AoC) Evan Williams said: "There have been longstanding question marks over the principals' pay element of the LSC College Accounts - which UCU are using as the basis for this analysis.
"Where one principal replaces another in-year the pay of two individuals is sometimes counted as one; data from one year has been attributed to that of another."
He added: "Notwithstanding data issues, college principals are paid less than vice-chancellors at universities with equivalent student numbers, for example, or the heads of private sector organisations with equivalent turnover.
"It is also important that colleges, which are complex, multi-million pound organisations, are professionally run - pay growth may well match growths in student numbers and income."
Recent reports suggest many colleges are facing sizeable budget cuts. A survey of 147 colleges by the AoC found 62 faced a cut of more than 20%.
The figures also come not long after public sector union Unison called for a legally enforceable cap to be placed on principals' pay.
BBC