A high pressure injection equipment (HPIE), which is an electronically controlled. hydraulic pressure intensified system that can produce 250MPa, has been developed. This equipment has been evaluated with shadow photographs for analyzing non-evaporating fuel spray characteristics. It was found that the fuel injected at high pressure forms a finer and more homogeneous spray. Then the HPIE has been fitted to a naturally aspirated 2 liter single-cylinder diesel engine and tested. It was found by the test that black smoke and particulate emissions decreased extremely, under suitable injection timing for low NOx emission. The emission test data at 220MPa of injection pressure shows that more than 80% reduction of particulate emission has been realized at the same NOx level as with a conventional jerk pump. These results indicate that the high pressure fuel injection is an effective means for reducing NOx, smoke and particulate emissions at the same time.