A reference frame obtaining method includes determining a first reference frame list and a second reference frame list of a current picture block, determining, from the first reference frame list, whether an X-directional reference frame x1 satisfying a condition A1 exists, determining, from the second reference frame list, whether a Y-directional reference frame y1 satisfying a condition B1 exists, and in response to determining that the X-directional reference frame x1 exists and determining that the Y-directional reference frame y1 exists, obtaining index values (R1, R2) of bidirectional reference frames of the current picture block.