Population structure is one of the important factors affecting photosynthetic efficiency and yield formation of crop plants. A 3 x 4 factorial field experiment with maize (Zea mays L.) was arranged in a split plot design with 4 replications. Three population densities (75000, 90000, 105000 plants/hm²) were assigned in the main plots, each of which was divided into four subplots to host the planting patterns: 1) even plant spacing in a conventional 60 cm row, 2) double plants in a triangle arrangement in the same 60cm row spacing, 3) even plant spacing in a twin-row arrangement with 50 cm within each twin-row and 70 cm row spacing between two twin-rows, and 4) similar to 3), but with double plants in a triangle arrangement within each row in the twin-row arrangement. During the grain filling period, photosynthesis and chlorophyll fluorescence parameters were measured. The results showed that under the high plant density, canopy apparent photosynthesis of double-plant planting pattern in the twin-row treatment was higher (P < 0.05) than that of the even plant spacing in the conventional 60 cm row spacing. With increasing plant densities, the values of Fv/Fm, and qP were all reduced slightly to significantly, there were larger reductions in the chlorophyll florescence parameters in twin-row than in single row planting patterns, and in double-plant planting pattern than in the equal-distance single row plant spacing. The 90000 plants/hm² density in double-plant planting pattern and twin-row spacing arrangement had the greatest canopy photosynthetic productivity and greater yield.