The University of Winchester believes it is the world’s first life-sized sculpture of the “inspirational” Swedish environmental activist.
But the students’ union said the funds could have been better spent.
The university said “no money was diverted” from student support or staffing for the project.
Winchester UCU president Megan Ball described Thunberg as a “fantastic role model to everyone, as someone who speaks loudly and proudly about important global issues” but said the union could not support the sculpture.
She said: “We’re in a Covid year, lots of students haven’t really had access to campus, lots of them are trying to study online and are in dire need of support.
“We are calling on the university to match the statue cost by committing £23,760 in additional funding to student support services across campus.
“We urge them to publicly face the critical issues which students are highlighting and provide a transparent breakdown of additional and existing financial support.”
The union also passed a motion describing the statue as a “vanity project”.