Abstract: The properties and laxative effects of banana insoluble dietary fiber( IDF) were investigated in this study. Results showed that the water holding capacity,swelling capacity,and volume density of IDF were 11.91 g / g,9.66 m L / g,and 0.345 g / m L respectively.The crystallinity of banana IDF was 66.14%. Banana IDF was bar fiber under scanning electron microscopy. IDF from bananas was constituted by rhamnose,galactose,xylose,arabinose,and glucose.It was discovered by animal experiments that banana IDF had laxative effects.Banana IDF at dose 4 g /( kg·BW·d) was able to accelerate the movement of the small intestine and was effective in shortening the time to the first black dejecta and quickening catharisis at the dose of 1 g /( kg·BW·d).Banana IDF significantly impacted the dejecta moisture content of mice,and the moisture content was positive correlated to IDF- dose.In conclusion,banana IDF had laxative effects.