Abstract Green forage is very important ingredient for animal feed either for meat cows or dairy cows. One of forage variety that now days becoming popularly used as animal feed is dwarf napier grass (Pennisetum purpureum cv Mott) because it has high productivity with short harvesting period. Cultivating dwarf napier grass is not difficult for the farmer, however harvesting this grass is quite difficult, hard work and generally still done manually by using a sickle. The purpose of this study is to design and evaluate performance of a harvesting machine for dwarf napier grass. Method of this research was common machine development method including functional and structural design analysis approaches. Performance test results showed that the machine was capable to harvest two rows of planting grass in one pass and average cutting height of 7.9 cm when using big tire and 8.6 cm when using small tire. The machine with large tire has Theoretical Field Capacity (TFC) 0.255 ha/hour, while its Effective Field Capacity (EFC) was 0.191 ha/hour and Field Efficiency (FE) was 75.01%. The result of performance test using small tire the TFC was 0.205 ha/hour, EFC was 0.145 ha/hour and FE was 71.04%. It was concluded that the newly modified napier grass harvester was satisfactorily designed and its performance increase harvesting efficiency.