Abstract: Flowering synchronization is essential for genetic management and deployment of clones in seed orchard. Studying variation and stability of flowering synchronization of clones among plant ages are helpful for further management of clones in present seed orchard and backward selection. Based on collected data of florescence period and flower number of 49 clones within a 13-year span in a seed orchard of Pinus tabulaeformis, the flowering synchronization of each clone in different investigated ages was estimated. Results showed that there were obvious differences of flowering synchronization among parent clone combinations. In general, flowering synchronization of clone as paternal was higher than it as maternal. Probability of selfing within clones were higher than out-crossing. There were moderate stability of flowering synchronization of clone as material among plant ages. So, clone selection by flowering synchronization of clone as material would be valuable in early flowering ages in seed orchard, but flowering synchronization of clone as paternal might be lower. Analysis of flowering synchronization of clones would be benefit for clone management in present seed orchard and refer to both genetic design and collocating design of parent for advanced seed orchard based on backward selection of clones.