Abstract: Abstract: In order to conduct research on the in-cylinder spray and combustion of an electrically controlled high pressure common-rail diesel engine, taking one high pressure common-rail diesel engine as the research object, a multifunctional dynamic visual experimental device was designed, which was used to collect in-cylinder dynamic combustion process images. On this basis, the intake port of the diesel engine was improved, and the fresh air was replaced by industrial purity nitrogen, so that the real-time dynamic multiple spray images were collected under single cylinder misfiring conditions. The study illustrated that the multiple injections-pre- injection, main injection, and post injection-can be clearly observed, including at the injection time, spray cone angle, and in the atomization situation. The pre-injection occurred at the ?25° crankshaft angle, and the duration was about 5° crank angle. At this stage, the quantity of fuel injection was less, and the atomization was not obvious. The main injection occurred at the ?10° crankshaft angle, and the duration was about 10° crankshaft angle. There was a large amount of fuel ejected from the nozzle, and the penetration force was strong. The spray cone angle and a significant oil beam could clearly be observed, which expanded to the bottom of the piston "ω" crown in line. The post injection occurred at the 8° crankshaft angle, the injection duration was shorter, and the amount of fuel injection was less, however, the atomization effect was obvious because of the higher temperature of the cylinder at this stage. In addition, when the diesel engine ignited, the flame center formation and flame propagation process could be captured in real time under different working conditions. The fuel spray was not fully discrete and mixed with air partly at the initial in-cylinder ignition time, which was the so-called pre-mixing ignition and occurred at ?15°- ?4° crankshaft angle. Near the TDC, the flame quickly spread and filled the combustion chamber fully along with the air flowing. Compared with the in-cylinder combustion image under rated conditions, the ignition time under idling conditions was delayed about 5° crankshaft angle, the flame occupied area was smaller, and there was lower brightness. The study provided a lot of in-cylinder information and experimental measurement means for research on the in-cylinder spray and combustion of an electronically controlled common-rail diesel engine, and the spray and combustion simulation results could also be verified by these experiments.