A single-shot imaging system with multiple frames has been developed, which can record sequential multiple frames by delaying multiple optical images with fiber bundles and then capturing the images with a single intensified camera. The observed optical object is imaged through four lenses onto the end faces of four sets of fiber bundles. These fiber bundles with different lengths can provide different delays for delivering optical images, which determine the inter-frame separation times. The optical images exported from the fiber bundles are captured with a single intensified CMOS camera simultaneously. This imaging system has been applied for investigating the dynamic x-ray spot of the rod-pinch diode via a combination of scintillators, which are used to convert x-ray images to optical images. Four sequential x-ray images in a single shot have been obtained, which show the dynamic development of the rod-pinch x-ray spot. The results experimentally reveal the dynamics of the electrons flow bombarding the rod, which roughly agrees with the theoretical modeling of the rod-pinch diode.