Abstract: In this study, alkali treatment was used to extract the fibers of Neosinocalamus affinis leaves. The effects of sodium hydroxide concentration, solid-liquid ratio, time and temperature on the extraction rate of dietary fiber from N. affinis were studied with single factor and orthogonal test, the optimal extraction technology of dietary fiber from N. affinis leaves was screened out, and the insoluble and soluble dietary fiber in bamboo leaf fiber were analyzed. The results showed that the content of crude fiber in bamboo leaf fiber increased with the increase of sodium hydroxide concentration. When the concentration of sodium hydroxide reached 10%, the highest content of crude fiber was 75.87%. When the solid-liquid ratio is 1∶15, the highest content of crude fiber is 76.37%. When the extraction time was 18 hours, the highest content of crude fiber was 76.20%; with the increase of temperature, the content of crude fiber in the extracted bamboo leaf fiber increased gradually, reaching the maximum of 75.93% at 40 ℃. The optimal extraction technology of N. affinis leaf fiber was A₂B₂C₁D₃, that was, the concentration of sodium hydroxide (10%), the solid-liquid ratio (1∶15), the extraction time (17 h), and the temperature (42 ℃). The concentration of sodium hydroxide, the solid-liquid ratio, temperature and time had extremely significant differences on the extraction rate of dietary fiber from N. affinis. With the optimal extraction technology, the extraction rate of N. affinis leaf fiber was (34.58±0.29)%, the crude fiber was (82.27±0.35)%, the soluble dietary fiber was (12.86±0.26)%, and the insoluble dietary fiber was (76.11±0.44)%. It was found that N. affinis is a new type of fiber source with development potential.