This present study investigates the performance and emission characteristics different injection pressure on variable compression ratio of a diesel engineusing cyanobacteria (greenalgae).In the Diesel Engine the experiments were controlled withvarious hole injection to study the effect onemission and performance by using conventional diesel future emission regulation will require substantial reductions of NOX and CO2 emissions from diesel engines. With cyanobacteria (green algae) as a biodiesel and diesel blends are prepared to use as fuel on variable compression ratio diesel engine.