According to the maize yield at plant density of 15000 ind x hm(-2) in 2007, the leaf-redundant type (cultivar Chaoshi 1) and non-redundant type (cultivar Chaoshi 3) at low plant density were selected, and the changes of their above-ground dry matter accumulation and grain yield after cutting all leaves to 1/2 (T1) and 1/4 (T2) at anthesis at the optimal density and under high-yielding condition were analyzed in 2008, aimed to approach whether the leaf redundancy exists in high-yielding maize colonies. The characters of grain-filling were simulated by Richards' model, and the photosynthetic characteristics and chlorophyll fluorescence of the leaves on ear position were determined to reveal the activities of photosynthesis after the removal of redundancy. The results showed that at optimal plant density and under high-yielding condition, both the redundant and non-redundant types had leaf redundancy. The characterization of grain-filling by Richards' model indicated that appropriately removing redundant leaves could increase the net photosynthetic rate and solar energy use efficiency of the leaves on ear position, extend the active period of grain-filling, and enhance the grain yield.