In this research, combustion and spray characteristics were investigated experimentally in a constant volume chamber by applying bio-diesel fuel to a common-rail system in which precise control is available for utilizing environmentally friendly properties of bio-diesel fuel. The experiment was conducted at fuel temperatures $20^{circ}C$ and $-20^{circ}C$ to investigate combustion characteristics of bio-diesel fuel provoking problems in fluidity specially in a low temperature. For the visualization, the experiment was carried out under various conditions of ambient pressure, injection pressure and fuel temperature. The test was made by three different types of diesel fuels, conventional diesel, BD20 and BD100. In summary, this research aims to investigate combustion characteristics in the application of bio-diesel fuels and compare the results with performance of conventional diesel fuel. This experimental data may provide fundamentals of spray and combustion of bio-diesel fuels at a low temperature and contribute to the development of bio-diesel engines in future.