Investigations were carried out with 54 adapted genotypes to study the relationships betwrrn major developmental phase durations and yield in speing wheat in a randomized-block experiment of 3 replicates in 1984 anb 1985.Cluster and path analyses were conducted on the phase durations and yield as well as other traits conserned.Results show that wheat yield is dependent mainly upon the reasonable ratio of different developmental phaes durations, though there is some contradiction between early-maturity and yield.Prophase and anaphase make much more contribution to yield formation than metaphase.The goal for breeding high-yield early varieties in middle regions of Jilin Province is to decrease metaphase largely and reduce anaphase moderately on the basis of a longer prophase, at the same time to promote hee transfer of organic matter from vegetative to reproductive organs and improve seed traits.