Circular rna and preparation method thereof

A circular RNA precursor comprising from 5′ to 3′ direction:

• a) a 3′ self-splicing intron fragment;
• and
• b) a 5′ self-splicing intron fragment;
• wherein the 3′ self-splicing intron fragment and the 5′ self-splicing intron fragment in combination retain the self-splicing activity of a self-splicing intron and allow generation of a circular RNA through the self-splicing of the circular RNA precursor, and
• wherein the self-splicing intron is selected from Group I introns and Group II introns.