A seedling culture method using a compacted straw seedling culture cylinder with a sleeved isolation pocket is characterized in that straw is compacted into a straw cylinder by an extrusion device, or a straw cylinder which is spliced and combined by straw tubes or straw rods by connecting a positioning device; or a straw bottom and a straw cover which are made of compacted straw are arranged in the straw cylinder in a matching way; the bottom of the straw cylinder is fixedly connected with the straw bottom through the positioning device to form a container, and the isolation pocket with ventilation function at the bottom is sleeved on the container; ventholes are uniformly arranged on the straw cylinder, the straw bottom and the straw cover; the container is filled with planting soil, the compacted straw cover is arranged on the surface layer of the planting soil after putting a plant to be planted, and the straw cover is covered with soil again and is watered; the compacted straw cylinders sleeved with isolation pockets are tightly arranged into a honeycomb shape, and the peripheries of the compacted straw cylinders are covered with soil or bricks. The device is easy to manufacture and install, can naturally and slowly release the fertilizer and emit carbon dioxide in the process of decay to facilitate the absorption of the leave surfaces of seedlings, meanwhile, the device self becomes less tight and has good air permeability performance to facilitate the growth of the root systems of the seedlings.