The invention provides a flexible double-tube water diversion, electricity generation and water storage integrated device suitable for rivulets in mountainous areas. The flexible double-tube water diversion, electricity generation and water storage integrated device suitable for the rivulets in the mountainous areas comprises an inlet sand sinking section, a water delivery section, a pipeline mechanical-electrical integrated electricity generation section and an outlet water storage section from top to bottom in sequence. The water delivery section is composed of two flexible pipelines and a water guiding port and a water outlet of each flexible pipeline are communicated with the inlet sand sinking section and the pipeline mechanical-electrical integrated electricity generation section respectively. Repair valves and sand sinking wells are arranged on the flexible pipelines, a mode of arrangement in sections is adopted by the flexible pipelines, and the repair valves are arranged among the sections of pipelines. The pipeline between the water guiding port and the water outlet of each flexible pipeline is arranged roughly along the same elevation of the mountain; an electricity generation mechanism is arranged in the pipeline mechanical-electrical integrated electricity generation section and the outlet water storage section is located behind the pipeline mechanical-electrical integrated electricity generation section. The flexible water delivery pipelines are combined with a rigidity pressure-bearing electricity generation pipeline and a pipeline mechanical-electrical integrated technology is combined, so that the integration of water guiding and electricity generation of small hydropower stations is achieved and the purposes of accelerating the speed of country hydropower establishment and reducing ecological environment destruction are achieved.