In order to explore the genetic response of planting density to the heterosis and combining ability of Io-dent inbred lines,and to provide a theoretical basis for dense planting and high yield cultivation.The NCII designwas applied to 30 cross combinations,and the heterosis and combining ability of 5 different lines of Iodent germ-plasm under different densities were studied.Under the density of 60 thousand,75 thousand and 90 thousandplants/ha,30 hybrid combinations yield strains of heterosis values were 128.5%,86.3%and 60.4%,CV were30.8%,25.8%and 29.9%.JK1101 GCA effect to yield was the highest under the density of 60 thousand plants/ha（9.55）,while JK1103 was the lowest （-6.85）;JK1103 GCA effect to yield was the highest（3.51） under the density of75 thousand plants/ha,while JK1102was the lowest （-4.83）;JK1103 GCA effect to yield was the highest under thedensity of 90 thousand plants/ha（3.95）,while JK1102 was the lowest（-5.57）.It was the only that the SCA effect val-ues of Dan340×JK1101 and JK33×JK1102 were positive under 3 densities,which were 9.84,8.72,22.68,6.33,1.49 and 19.15,respectively.The GCA effect of Iodent germplasm in different strains was different under differentdensities.The yield of GCA under the density of 75 thousand and 90 thousand plants/ha had the same trend,whichwas a significant positive correlation;The SCA effect of the same combination that crossed by Iodent germplasmstrains was not consistent with the changing direction of the increase and decrease of the test density.