A real-time and in situ optical measuring system is developed, which can be used to observe the deformation of structures under impacting loading. The system consists of the high-speed camera, digital acquisition, laser light source, synchronization controlling system and analysis software based on the digital correlation theory. The optical system has been adapted to investigate the dynamic deformation fields of normal impact tension sample and plain plate with notches loaded by split Hopkinson tension device. Results obtained in experiments are discussed and compared with finite element simulations and classical Hopkinson bar method. It is proved partly that the measuring system, developed in this paper, is effective and valid.