Abstract: Abstract: Banana stalk is the main byproduct of bananas after post-harvest, and is mainly decayed naturally or discarded in the field, due to large stalk, high moisture content and other characteristics, resulting in a great waste of resources and an environmental pollution problem. Meanwhile, banana stalk contains high-quality plant fiber, which is lightweight, with strong permeability, also has high economic value, which is suitable for the production of medium and top-grade products, such as suits, shirts, ties, and various decorations, as well as fine paper. So far, the domestic and foreign research on fiber extraction and application mostly concentrates in rice straw, corn stalk, cotton stalk, biogases, or pineapple leaf, etc. Drawing on the previous studies, water immersion method, biochemical and mechanical extraction method and other methods are available, but just the immersion method and the biochemical method are mainly adopted by researchers. Domestic mechanical extraction of banana stalk fiber is still in its infancy, due to its regional characteristics, particularly for fiber extraction machinery, which is rarely reported both at home and abroad. Based on the above issues, a banana fiber extracting machine with a hybrid of rolling and smashing was put forward and designed in this paper, which was mainly composed of a conveying device, rolling device, rolling device Ⅱ, smashing device, machine cover, walking wheel, drainage pipe, motor, and machine chassis. During the working period, banana stalk was conveyed to a rolling device Ⅰ via conveyor belt, and crushed first through the relative rotation of the upper roller and lower roller (distance between two rollers of 5-10 cm). Then, it was conveyed to rolling device Ⅱ, and was crushed secondly through the relative rotation of the upper roller and lower roller (distance between two rollers of 2-5 cm). After the above two steps, more than 80% of water was extruded, and was discharged through the drainage device. Then, the crushed banana stalk was smashed by high-speed knives in the smashing device. Finally, the processed banana fiber was discharged through the lower bezel. Referring to the current situation, the paper designed the rolling and crushing combined type extracting machine for banana stem fiber. It gave the main structure of some components including drive system, rolling device I, rolling deviceⅡ, crushing device and motor, and simulated the crushing knife by finite element analysis. The sample test results showed as below: the passing rate of fiber rubbing objects was 89.2%, the impurity rate was 8.6%, the output was 206 kg/h, and the energy consumption was 20.2 kW·h/100kg. The research indicates that the design meets the requirements. Compared with the half feeding type extracting machine for banana stem fiber, the rolling and crushing combined type extracting machine for banana stem fiber improved the passing rate of fiber rubbing objects by 8.1%, decreased the impurity rate by 6.5%, improved the output by 71.7%, and decreased the energy consumption by 10.6%. Successful implementation of this project will lay a solid theoretical design of high performance to adapt to the field of banana stalk fiber extraction machines, and will have important practical significance to promote the sustainable development of the tropical agricultural areas in China.