Abstract: The effects of the population density on the yield characters and their heterosis in four T-type hybrid wheats were studied, The results indicated that all characters existed significant differences among densities, The number of ears per plant，the number of kernels per ear and 1000-kernel weight decreased as density increased.Grain yield and density showed quadratic parabola relationship, The direct effects of heterosis of average number of kernels per ear and number of ears per plant were higher in the lower density than in the higher density，while that of 1000-kernel weight was lower in the lower density than in the higher density in the formation of heterosis of yield.The aptimum range of population density in hybrid wheat is found to be 85-130 thousands plants/m u，which was determined by solving the simultaneou s standardized equations of the yield and its heterosis and also by finding the derivative of the yield regression equations,Adopted cultivating measures were suggested when the population density of hybrid wheat was decreased appropriately.

Key words: Hybrid wheat, Heterosis, Sowing density