This paper presents an experimental study on the effect of double injection strategies on combustion characteristics in a single-cylinder diesel engine. These studies are applied to the double injection strategies, such as 2nd injection timing variations with fixed injection interval (8 degree) and variations of injection pressures with fixed injection timing and intervals. The injection quantity was 7+7mg for double injections, and 14 mg for single injection. When the injection pressure was increased, the ignition delay was shortened, and the ISFC (indicated specific fuel consumption) was increased due to the fast termination of combustion by the shortened energizing duration. In addition, the retardation of injection timings toward TDC (top dead center) caused the reduction of ignition delay and the decrease of ISFC with the decrease of FMEP (friction mean effective pressure).