To understand the coupling effects of needle valve wobbling and residual bubbles on the nozzle internal flow and near field in diesel engines, high-speed microscopic imaging technology was employed to study the dynamics behaviors of a real-size tapered hole nozzle. Research results indicated that during the pre-injection and post-injection process, the difference in throttling effect caused by the wobbling of the needle valve is the main reason for the instability of the fuel injection quantities. As the pulse widths increases, the actual injection duration and the maximum needle valve lift increased, so that the throttling position changes from the passage between the needle valve and the needle seat to the nozzle holes, and the cavitation mode changes from geometrically induced cavitation to string cavitation. During the main injection stage, the spray cone angle and spray area ratio showed a boot-shaped trend of firstly low and then high, forming a development stage, a transformation stage and a stable stage. And in the initial stage of injection, the spray pattern is affected by the combined influences of the axial momentum and radial momentum of the injected fuel, resulting in a difference between the second spray disturbance and the primary breakup.