1. A retractable dual-purpose file folder, comprising: a retractable chamber, comprising a front panel, a rear panel, a retractable bottom wall, two retractable side walls and an accommodation space; a plurality of three-sided sealed spacers, arranged at intervals into the accommodation space of the retractable chamber, a bottom of the three-sided sealed spacers being coupled onto the retractable bottom wall, both sides of the three-sided sealed spacers being coupled onto two retractable side walls; at least two multi-section locators, being comprised of a first locator and a second locator, said first locator arranged onto the front panel of the retractable chamber, said second locator arranged on the rear panel of the retractable chamber; at least two positioning bands formed by an elongated band, each positioning band having a positioning end and a moveable end, each positioning end located securely below the first locator specific to the front panel of the retractable chamber each moveable end having a mating portion at the moveable end mated securely with the first and second locators, moreover, the moveable end passing through a band limiting portion preset at lower part of the rear panel of the retractable chamber, said band limiting portion comprising an upper long hole and a lower long hole arranged in parallel.