The goal of this study is to establish relationships between the hot compression deformation behaviors and the fractal dimension of primary phase morphology of TA15 titanium alloy using the analytical methods of metallurgical microscope and transmission electron microscope coupled with box-counting dimension method. The hot compression deformation behaviors vary with decreasing fractal dimension owing to the change of microstructure caused by different parameters of the hot compressive deformation. The results indicate that TA15 alloy shows dynamic recrystallization characteristics at deformation temperature lower than 850°C while fractal dimension exhibits a moderate decreasing trend with the temperature increasing, and shows dynamic recovery characteristics at deformation temperature higher than 850°C while fractal dimension reduces rapidly with the temperature increasing. The fractal dimension displays non-linear relationship with fraction of primary phase and with aspect ratio of primary phase. © Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg 2011.