The 'Halo' hitmaker headlines the world-famous music event in Somerset, South West England, on Sunday (26.06.11) and is determined to give the best show she can, so has been throwing herself into preparations.
A source said: "She's been working hard. She wants her and her dancers' routines to be perfect and doesn't want to get a foot wrong."
However, the 29-year-old star plans to end her preparations today (24.06.11), so she and husband Jay-Z - who controversially topped the bill at the event in 2008 - can enjoy the music at the festival, which is headlined tomorrow (25.06.11) by U2 and on Saturday (26.06.11) by Coldplay.
The insider added to The Sun newspaper: "By tomorrow she won't be doing any more rehearsing. She'll be relaxing with Jay-Z and they'll head to Glastonbury together."
Beyonce - who joined Destiny's Child when she was just 14 - previously revealed her dedication to her career meant she didn't have many friends.
She said: "Socially I did miss out. I left school at 14 and had a tutor. I was never exposed to people long enough to make friends so my family became my friends."