In this research, it was investigated how the combine harvester forward speed and the rotation of blades during sunflower harvest affect chopping efficiency and fuel and power consumption of the chopping apparatus placed under the harvesting header. The optimal forward speed and the rotation of the blades were determined by carrying out field experiments. In field experimental studies, the best results in terms of chopped stalk size distribution were obtained with the forward speed of 7.5 km h-1and the blade rotation of 1500 min-1 and 2000 min-1. At the forward speed of 7.5 km h-1, the variation coefficient of blade rotation at 2000 min-1 was lower than the value at 1500 min-1. At the high forward speed and the high blade rotation, the chopped stalk size has been increased. At the combine harvester that the chopper system was used, the experiment results at forward speed of 7.5 km h-1 were better than the results at 5 km h-1 and 10 km h-1 in terms of chopped stalk size. At lowest forward speed of 5 km h-1, average power requirement was 6.6 kW with a fuel consumption of 0.58 l h-1, whereas at the highest forward speed of 10 km h-1, average power requirement was 13.8 kW with fuel consumption of 1.16 l h-1.