A packaging method for organic semiconductor device, comprising steps of: manufacturing an organic semiconductor device on a flexible base; forming a photoresist block having a predetermined interval with respect to the organic semiconductor device and located at two sides of the organic semiconductor device on the flexible base; depositing an inorganic layer on the photoresist block, the organic semiconductor device and the flexible base; removing the photoresist block and the inorganic layer on the photoresist block; and depositing an organic layer on the inorganic layer disposed on the organic semiconductor device, the step of forming the photoresist block comprises steps of: coating a photoresist layer on the organic semiconductor device and the flexible base; using a predetermined mask plate to perform an exposure to the photoresist layer, wherein the mask plate includes a light-shielding portion and a light-transmitting portion respectively located at two sides of the light-shielding portion, the light-shielding portion is disposed above the organic semiconductor device, two sides of the light-shielding portion respectively extend beyond two sides of the organic semiconductor device, and a projection of the organic semiconductor device on the light-shielding portion is fully inside the light-shielding portion; and developing the photoresist layer after being exposed in order to remove the photoresist layer corresponding to the light-shielding portion so as to form the photoresist block. manufacturing an organic semiconductor device on a flexible base; forming a photoresist block having a predetermined interval with respect to the organic semiconductor device and located at two sides of the organic semiconductor device on the flexible base; depositing an inorganic layer on the photoresist block, the organic semiconductor device and the flexible base; removing the photoresist block and the inorganic layer on the photoresist block; and depositing an organic layer on the inorganic layer disposed on the organic semiconductor device, the step of forming the photoresist block comprises steps of: coating a photoresist layer on the organic semiconductor device and the flexible base; using a predetermined mask plate to perform an exposure to the photoresist layer, wherein the mask plate includes a light-shielding portion and a light-transmitting portion respectively located at two sides of the light-shielding portion, the light-shielding portion is disposed above the organic semiconductor device, two sides of the light-shielding portion respectively extend beyond two sides of the organic semiconductor device, and a projection of the organic semiconductor device on the light-shielding portion is fully inside the light-shielding portion; and developing the photoresist layer after being exposed in order to remove the photoresist layer corresponding to the light-shielding portion so as to form the photoresist block. coating a photoresist layer on the organic semiconductor device and the flexible base; using a predetermined mask plate to perform an exposure to the photoresist layer, wherein the mask plate includes a light-shielding portion and a light-transmitting portion respectively located at two sides of the light-shielding portion, the light-shielding portion is disposed above the organic semiconductor device, two sides of the light-shielding portion respectively extend beyond two sides of the organic semiconductor device, and a projection of the organic semiconductor device on the light-shielding portion is fully inside the light-shielding portion; and developing the photoresist layer after being exposed in order to remove the photoresist layer corresponding to the light-shielding portion so as to form the photoresist block.