Using Heavy Fuel Oil (HFO) is a practical measure to reduce running cost of high-speed diesel engines. Extending application of HFO would be great helpful to mitigate nation wide energy shortage problem. The authors attempted a set of experiments with a view to demonstrating the performance of a high-speed diesel engine fuelled with fuel blend of HFO and Light diesel (HFO-L) and water emulsified HFO-L. A number of experiments on test bench were carried out to check power performance, fuel economy and combustion performance of the engine. The results indicate that it is practicable to use HFO-L fuel blend on high-speed diesel engine without many additional modifications on engine structure. Compared with HFO-L, water emulsified HFO-L has better combustion performance, and thus better fuel economy as well as low harmful emissions. In addition, compared with using light diesel fuel, when using emulsified HFO-L blend, the engine can be operated with the same power performance, but with higher the brake specific fuel consumption. Whereas, considering much lower price of heavy fuel oil, the fuel economy is greatly improved.