Traits of differentiation,retrogression and formation on branch and spikelet in hybrid rice panicle were investigated at heading with 19 combinations sowed at different dates in the field,and the difference of the traits and their interrelations for the different seasons were analyzed.The results were as follows: there were considerable differences for differentiated primary branch(DPB),differentiated secondary branch(DSB),differentiated spikelet(DS),retrograded primary branch(RPB),retrograded secondary branch(RSB),retrograded spikelet(RS),percentage of retrograded primary branch(PRPB),percentage of retrograded secondary branch(PRSB),percentage of retrograded spikelet(PRS),survived primary branch(SPB),survived secondary branch(SSB),survived spikelet of primary branch directly(SSP),survived spikelet of secondary branch(SSS) and total survived spikelet(SST) among combinations and seasons,while differences of total survived spikelet(SST) under different seasons ranged 5.12%-93.59% and the average variation value of the total 19 combinations was 34.19%.Generally,variation of the traits of secondary branch under different seasons was the highest,that of spikelet was the second,and that of primary branch was the lowest.Aiming at the variability of the traits of differentiation,retrogression and formation on branch and spikelet in rice panicle under different seasons,the selections and utilization of new hybrid rice breeding resources from the point of view on large panicle were discussed.