Abstract: Abstract: 4LZG-3.0 millet combine harvester is developed to cope with the inadequacy in mechanized harvesting in millet. The major design is given in details. The header, conveyer, threshing system and cleaning system are designed, and their key parameters are calculated. The header dedicated for millet has a length of 580 mm. The crop dividers have their top points more than 1 300 mm above the ground, and foremost point over 700 mm from the knife bar. Inner and outer divider bars are added to the left crop divider, which are located at a distance of 100-120 mm from the side of the crop divider. The height of the center of the reel is over 1 100 mm, and has an adjustable region of 500-600 mm. The rotary speed of the reel is 30-34 r/min. The diameter of the feeder auger is 330 mm and the rotary speed 170 r/min. The original problems of crop stacking on the side of the header, ear dropping off and crop clinging to the reel are thus solved, and the header loss is significantly reduced. The threshing system has the structure of double transverse axial flow with D-type rasp bar. The entry clearance is 15-20 mm and the exit clearance is 2-4 mm. The concave is a grating one. The front conclave has a bar distance of 9 mm and the rear one 12 mm. The rotor speed is 850-970 r/min. By modifying the parameters mentioned above, the carry-on loss is reduced compared to other millet threshing systems while maintaining the grain breaking during the threshing procedure at a low level. Centrifugal fan with 3 kinds of available speeds and double-wire sieve is used in the cleaning system. The pore of the upper sieve is 14 mm × 14 mm and that of the lower sieve is 6 mm × 6 mm. The newly designed cleaning system has a drop in cleaning loss. A broken spike recycling device is developed to recollect capes and heavier broken stalk from the residual. This recycling device can be added to the machine as an attachment when required, as in some regions such materials are demanded as forage. Major parameters of the millet harvester are as follows. The engine power is 55 kW, the cutting width 2.0 m, the capacity ≥ 3.0 kg/s, the productivity 0.23-0.45 hm2/h, the rubber track 400 × 90 × 48 (mm × mm × segment), and the wheelbase 1 080 mm. The field experiment and performance test results show that this harvesting machine has achieved a stable performance. The main indices tested in the standard working condition are as follows. The feeding amount is 3.30 kg/s, the total loss rate 6.89%, the impurity rate 1.8%, the broken rate 1.4%, the productivity 0.4 hm2/h, and the equipment reliability coefficient 95%. Each of the indices has reached or exceeded the designed technical specification. It is concluded that the millet combine harvester is suitable for harvesting small-grain crops like millet, with superiorities such as large capacity, low header and threshing loss rate and little impurity for the grain. It can save operation time by over 90% while reducing labor intensity, promoting efficiency and cutting cost compared to manual harvesting. This study has provided a reference for millet mechanical harvesting.