A woman has stormed, wailing, from a Sydney court after a youth who doused her with petrol and set her alight in an inner-city alley was sentenced to a minimum of three years' jail.

The woman, a Korean national known as "Miss K", suffered burns to 45 per cent of her body on March 22, 2012, when the youth forced her to the ground, doused her with a milk carton full of petrol, and then set her alight as she tried to flee.

The woman being taken to hospital after being set alight in Chippendale in 2012. Credit:Channel Ten

Miss K, a student in her 30s, has had five operations, including one to remove her upper lip, which was undertaken in a bid to treat the severe burns to her face.

The youth cannot be named because he was 17 at the time of the attack, but is referred to as "MF".