A method of coding a current field macroblock in a B-frame, comprising: obtaining a reference frame picture list including multiple reference frame pictures; determining a reference frame picture index of the multiple reference frame pictures in the reference frame picture list based on display order information for the multiple reference frame pictures, reference frame picture index numbers being allocated in a display order to reference frame pictures whose display order is higher than a display order of a current frame picture and remaining reference frame picture index numbers being allocated in a reverse order to reference frame pictures whose display order is lower than the display order of the current frame picture, wherein the current frame picture includes the current field macroblock; reordering the reference frame picture index allocated to each reference frame picture in the reference frame picture list; obtaining motion vector information for the current field macroblock; characterized by obtaining a reference field picture index associated with the current frame picture including the current field macroblock by alternately allocating reference field picture indexes that are increased by one to reference field pictures, starting from a first reference field picture having a parity equal to a parity of the current field macroblock to a second reference field picture having a parity different from the parity of the current field macroblock, while starting from a reference field picture index value of "0" and a reference frame picture having a reference frame picture index value of "0" and sequentially visiting the multiple reference frame pictures according to the order of the reordered reference frame picture index, such that the reference field picture index is related to the reordered reference frame picture index according to following equations: - reference field picture index = reordered reference frame picture index *2 when a field having a same parity as the current field macroblock; and - reference field picture index = reordered reference frame picture index *2 + 1 when a field having a different parity as the current field macroblock; and performing motion compensation the current field macroblock in the B frame by using a reference field picture indicated by the reference field picture index and the motion vector information for the current field macroblock. obtaining a reference frame picture list including multiple reference frame pictures; determining a reference frame picture index of the multiple reference frame pictures in the reference frame picture list based on display order information for the multiple reference frame pictures, reference frame picture index numbers being allocated in a display order to reference frame pictures whose display order is higher than a display order of a current frame picture and remaining reference frame picture index numbers being allocated in a reverse order to reference frame pictures whose display order is lower than the display order of the current frame picture, wherein the current frame picture includes the current field macroblock; reordering the reference frame picture index allocated to each reference frame picture in the reference frame picture list; obtaining motion vector information for the current field macroblock; characterized by obtaining a reference field picture index associated with the current frame picture including the current field macroblock by alternately allocating reference field picture indexes that are increased by one to reference field pictures, starting from a first reference field picture having a parity equal to a parity of the current field macroblock to a second reference field picture having a parity different from the parity of the current field macroblock, while starting from a reference field picture index value of "0" and a reference frame picture having a reference frame picture index value of "0" and sequentially visiting the multiple reference frame pictures according to the order of the reordered reference frame picture index, such that the reference field picture index is related to the reordered reference frame picture index according to following equations: - reference field picture index = reordered reference frame picture index *2 when a field having a same parity as the current field macroblock; and - reference field picture index = reordered reference frame picture index *2 + 1 when a field having a different parity as the current field macroblock; and performing motion compensation the current field macroblock in the B frame by using a reference field picture indicated by the reference field picture index and the motion vector information for the current field macroblock. - reference field picture index = reordered reference frame picture index *2 when a field having a same parity as the current field macroblock; and - reference field picture index = reordered reference frame picture index *2 + 1 when a field having a different parity as the current field macroblock; and performing motion compensation the current field macroblock in the B frame by using a reference field picture indicated by the reference field picture index and the motion vector information for the current field macroblock.