The invention discloses a flexible organic semiconductor laser and a manufacturing method thereof. A device structure comprises an elastic substrateinterface modification layerorganic semiconductor laser gain medium, wherein the elastic substrate is highly elastic plastic, such as Polydimethylsiloxane (PDMS), polyurethane acrylate (PUA), polyving akohol (PVA), etc.; the interface modification layer is an organic polymer interface modification layer filmed by a solution, such as cellulose acetate (CA), polyelectrolytes (PEs), conjugated polyelectrolytes (CPEs), etc.; the organic semiconductor laser gain medium is a laser material possessing optical characteristics. The manufacturing method comprises coating the interface modification layerorganic semiconductor laser gain medium on the elastic substrate through a solution method, the solution method comprising spin coating, spray coating, silk-screen printing, ink-jet printing, etc. The laser prepared according to the method has excellent combination properties, including low light amplification spontaneous radiation threshold (ASE), and sound flexibility (the threshold maintains stable when the laser is bended and distorted randomly or even stretched).