A cascaded under-driven artificial finger of robot for simulating human finger has an active slide block inlaid in the first finger segment, a middle joint with the gear axle between the first and second finger segments and fixed to the second finger segment and the gear engaged with rack bar, the small and big gears on a single axle which along with two gear axles of middle joint are on the first finger segment, a synchronizing belt with lower gear fixed to small gear axle and upper gear fixed to the final joint axle on the second finger segment, and the third finger segment on the final joint axle.