James Constable's brace handed Oxford a point and ensured that Barnet remain in the League Two relegation places.
Clovis Kamdjo converted Mark Byrne's free-kick at the far post to give the hosts hope of beating the drop.
The unmarked Constable drew his side level shortly afterwards, only for the Bees to go in front again through Mark Hughes' cross-shot.
And Constable tapped in Josh Payne's cross late on to prevent the Bees moving out of the drop zone.
Barnet are one point behind 22nd-placed Northampton in the table with just two games remaining.
Oxford are in 12th position with a goal difference of zero.
Barnet boss Giuliano Grazioli told BBC London 94.9:
"The attitude they showed, well as a manager, you can't ask for more than that.
"Our first half display was very good and we should have gone in ahead, overall they all put a shift in and I can't ask for more.
"We didn't create too many chances but we thoroughly deserved the draw maybe even the win."