Abstract: Flowering phenology characteristic of Populus euphratica and Populus pruinosa in different populations was studied.The results showed that:flowering phenology of male trees was earlier than that of female ones in all populations of P.euphratica and P.pruinosa.Generally,the beginning of female bud burst time was 1-4 days later and the end was 2-5 days later than those of male bud burst time,respectively.The overlap period of male and female bud burst time was longer.In the same population,the inconsistency of inflorescence were relatively high among same gender of P.euphratica or P.pruinosa.Compared P.euphratica with P.pruinosa,flowering time of P.euphratica population was 2-5 days earlier than that of P.pruinosa.According to cumulative distribution of flowering individuals each day,the male and female bud burst time of P.euphratica was bimodal type,and that of P.pruinosa was unimodal type.