The invention provides an efficient separation method for low-grade and complex iron ores. The method is characterized in that the complex iron ores of different grades and species are classified, so as to obtain lump ores and mineral powder which are balled, dried and preheated; reduction roasting, cooling, ball milling, magnetic separation, ball milling and magnetic separation or reverse flotation are performed in turn, so as to obtain iron ore concentrate or reduced iron powder; classification treatment is to crush and screen the iron ores with iron-containing grade between 50 and 56 percent and then dry and preheat obtained ores; fine-grained mineral powder is ground, washed, ground, deslimed and separated so as to obtain the iron ore concentrate and slime containing 58 to 60 percent of iron; the slime which is washed, deslimed, and separated is dewatered and dried and is added to and well mixed additives, so as to be balled then; the iron ores with the iron-containing grade between 40 and 50 percent are crushed and screened so as to obtain the lump ores which are directly dried and preheated, while the fine-grained mineral powder is obtained through dry-type grinding and then is added to and well mixed the additives so as to be balled then; and the iron ores with the iron-containing grade between 25 and 40 percent are crushed and screened so as to obtain the lump ores which are dried and preheated, while the fine-grained mineral powder is subjected to grinding, gravity separation or high-gradient magnetic separation and reverse flotation, so as to obtain coarse iron concentrate powder which is added to and well mixed with the additives and then is balled.