Abstract: Phosphoinositide-specific phospholipase C (PI-PLC) is a conserved key enzyme in phosphoinositide signaling for animals and plants. It plays an important role in growth and development, as well as various abiotic and biotic stresses in the organisms. Based upon the existing database and bioinformatics methodologies, PI-PLC family gene structures and their positions on chromosome and duplication for poplar (Populus trichocarpa Torr. & Gray) (Pt) were obtained. PI-PLC proteins were classified according to their phylogenetic relationship. The results showed that 7 PtPLC genes existed in the poplar genome on 4 chromosomes. Their multiple alignments and motif displays indicated that all of the PtPLC proteins contained 4 conserved domains (i.e., EF, X, Y, and C2). Phylogenetic analysis on the PtPLC family classified them into two groups. The information would be the basis for a study on the functions of PtPI-PLC gene family.