The purpose of this study was to evaluate fuel efficiency of tractor using working cycle. First, baler operation was conducted in Italian ryegrass farmlands and engine torque and fuel consumption were measured as field data. Second, baler operation cycle was developed using the field data. The arbitrary working cycles were generated by randomly selected micro–trips, minimum working patterns. Some of the arbitrary working cycles were selected and baler operation cycle was determined considering sum of squared difference (SSD). The baler operation cycle was evaluated using performance value (PV) comparing with driving cycles. The results showed that PVs of the driving cycles were 67 ～ 109% of the baler operation cycle. Third, fuel efficiency of the baler operation was evaluated by dynamometer test using dynamometer system and the baler operation cycle. The fuel consumption and engine power were measured while the engine acted on the baler operation cycle and fuel efficiency was evaluated. The results of t–test showed no significant difference between fuel efficiency by the dynamometer test and fuel efficiency of each farmland by the field test. Considering all results of this study, the baler operation cycle is feasible to apply to evaluate fuel efficiency of tractor with dynamometer system.