The 27-year-old plays Daisy Buchanan in Baz Luhrmann's adaptation of F Scott Fitzgerald's iconic novel, reported Digital spy.
"Daisy is kind of a tricky character, because she contradicts herself constantly, but she's also not very consistently laid out. She's eccentric, but seems to feel things passionately, but not necessarily for very long," Mulligan said.
The actress who has previously appeared in films such as "Shame", "Drive" and "Never Let Me Go" among said that "The Great Gatsby" was by far the biggest movie she has worked on.
"The Great Gatsby" is slated for a release in the US on May 10 and in UK on May 16.