Abstract: Abstract: To date, there is little information on the degumming technology by Streptomyces lydicus for banana fibers destined for textiles. Furthermore, the retted efficiency and characterization of banana fiber has not yet been found in literatures. In this study, banana fiber (Musa spp. Baxijiao) bio-degumming at laboratory scale with controlled inoculation using selected strain (Streptomyces lydicus) and physicochemical characteristics of retted banana fiber were investigated. The hydrolysis activity of selected strain was conducted by pectin and hemicelluloses culture. Clear zones were visualized on pectin-agar and hemicelluloses-agar plates. Effect of fermentation conditions (temperature, pH, nitrogen source, carbon source and inoculums size) on banana fiber degumming was evaluated based on the content of residual gum and activity of pectin lyase. The results indicated that the optimum degumming medium of strain was pH value 5.0, NH4NO3 4 g/L, wheat bran 10 g and inoculums size 9 mL. After cultivating for 72 h, the activity of pectinase was 75 μg/(mL·min), the residual gum of banana fiber was 4.86%, the yield of retted banana fiber was 59.48% (dry weight). Structural and surface analysis of the degumming banana fibers showed a reduction in diameter and changes in surface morphology from that of the raw fibers. The average range of the fiber diameters were approximately 5-10 μm, which was lower (p<0.05) than the average size of the fiber bundles before treatment. This reduction in the fiber diameter was due to the dissolution of hemicelluloses and lignin, which was confirmed by the chemical analysis and Fourier Transformation Infrared Spectroscope (FTIR) graphs. The treated fibers showed higher (p<0.05) percentages of cellulose (43.13% to 69.88%) and lower (p<0.05) percentages of hemicelluloses (18.85% to 10.89%), lignin (14.05 to 9.06), pectin (3.43% to 1.91%), and wax (12.24% to 5.77%) compared with untreated fibers. The physical property of fibers were analyzed according to the GB standards(GB5889-1986) and showed an increase in fineness (18.55 to 8.91 tex), and a decrease in break strength (345.37 to 237.37 cN) for the retted fibers. A small weight loss was found from 50 to 100℃, and this loss was primarily attributed to moisture and solvent evaporation or to the low-molecular- weight compounds remained after the isolation procedures. The fiber thermal stability for temperature ranging between 200 and 300℃ was primarily due to the depolymerization of non-cellulose, such as hemicelluloses, and the cleavage of glycosidic linkages of cellulose to form levoglucosan (1,6-anhydro-β-D-glucopyranose) and carbon residues. The decomposition of lignin occurred in the region from 200 to 500℃. The thermogram of the raw banana fiber indicated a greater resistance to degradation in the range of 354 to 527℃ due to the presence of larger amounts of hemicelluloses and lignin, the maximum degradation rate was found during the α-cellulose decomposition of raw and treated banana fibers at 287.45 and 349.04℃ (mass loss = 87.24%), respectively. The thermal analysis showed that the thermal stability of the treated fibers was improved. The XRD pattern of retted fiber, which exhibited an increased crystallinity (11.8% to 52.6%), gives a relatively intense peak at 2θ = 23.87°, and hydrolysis took place preferentially in the amorphous region. In all, the results showed that the Streptomyces lydicus stain had good applying prospects in microbial retting and enzymatic retting of banana fiber.