In high-energy flash radiography,scattered photons degrade the acquiring image,which limits the resolving power of interfaces and density of dense object.The application of large anti-scatter grid can reduce the scattered photons remarkably,but this requires a stable source position in order to reduce the loss of signal photons in the grid structure.The pinhole imaging technique is applied to observe spatial jitters of a triple-pulse radiographic source of a linear induction accelerator.Numerical simulations are conducted to analyze the imaging performance with the same or close parameters of the pinhole object and experimental alignment.Experiments are carried out to observe spatial jitters of the source between different measurements.Deviations of the source position between different pulses are measured in each experiment. In high-energy flash radiography, scattered photons degrade the acquired image, which limits the resolving power of interfaces and density of dense object. The application of large anti-scatter grid can reduce the scattered photons remarkably, but this requires a stable source position in order to reduce the loss of signal of photons in the grid structure. pinhole imaging technique is applied to observe spatial jitters of a triple-pulse radiographic source of a linear induction accelerator. Numerical simulations are conducted to analyze the imaging performance with the same and close parameters of the pinhole object and experimental alignment. Experiments are carried out to observe spatial jitters of the source between different measurements. Deviations of the source position between different pulses are measured in each experiment.