Objectives: To study the genetic mechanism of heterosis using two CSSLs test population in maize.Methods: In this study,a set of 184 CSSL(chromosome segment substitution lines),derived from a cross between inbred line lx9801(as the recurrent parent)and inbred line Chang72(as the donor parent),were used as male parents to construct two test populations with Zheng58 and Xun9058 as the female parents,and the heterosis of each F1 hybrids was estimated by comparing the male parent CSSLs.Filed experiments were carried out across two different environments in Henan to evaluate the plant height and ear height in the 184 CSSL and each corresponding F1 hybrids.Results: There were 24 and 29 different heterotic loci(HL)identified for plant height and ear height in the two populations.Three HL(hlPH4a,hlPH7c,hlPH1b)for plant height and three(hlEH1d,hlEH6b,hlEH1b)for ear height were identified in the CSSLs × Zheng 58 and CSSLs × Xun9058 populations as contributing highly to heterosis performance of plant height and ear height across four environments.Among the 29 HL identified for ear height,12 HL(41.4%)shared the same chromosomal region associated with the HL(50.0%)identified for plant height inthe same test population and environment.Conclutions: The CSSLs test population could be a powerful genetically segregated population for heterosis study; plant height and ear height may likely have the same additive and dominant genetic mechanism in maize.