NOVELTY - Preparing organic selenium-enriched cowpea, comprises (i) sowing, and seedling by filling soil on a seedbed; (ii) preparing selenium-enriched fertilizer by grinding organic selenium fertilizer raw materials, stirring, adding selenium fertilizer additive, stirring, adding effective microorganism inoculant, composting, and adding nitrogen-phosphorus-potassium; (iii) planting seeds in soil applied with as basal fertilizer rich in selenium, where the amount of basal fertilizer added is 20-30 kg/acre; (iv) planting cowpea, and watering; (v) carrying out field management; and (vi) harvesting.    USE - The method is useful for preparing organic selenium-enriched cowpea (claimed).    ADVANTAGE - The method meets the growth and development of cowpea based on normal growth conditions; does not require utilization of chemical fertilizers; saves fertilization period, and labor intensity; and reduces the dosage amount of selenium fertilizer, and multi-application of selenium causing environmental pollute.    DETAILED DESCRIPTION - Preparing organic selenium-enriched cowpea, comprises (i) sowing, and seedling by filling soil on a seedbed, covering soil up to a thickness of 10 cm, sowing cowpea seeds by digging socket, where 3-4 seed pieces are sowed/l, and covering fine soil up to a thickness of 4 cm, watering, and transplanting with soil once the seedlings have a pair of true leaves; (ii) preparing selenium-enriched fertilizer by grinding organic selenium fertilizer raw materials in a mill, uniformly stirring, then adding selenium fertilizer additive, stirring, adding water until the formation of blocks manually with less amount of water, and then adding lime into the material to adjust the pH to 6.7-7.3, adding 0.001-0.01% effective microorganism (EM) inoculant, stirring, covering the material with a plastic film, composting for 7-10 days, turning the materials once every morning and afternoon, during composting, to obtain compost, uniformly adding nitrogen-phosphorus-potassium (NPK) based on mixed microbial fertilizer in a ratio of 25-50:1-5:0.1-0.5; (iii) choosing deep soil layer rich in organic matter, soil and having easy irrigation and drainage property, and planting the seeds in soil for 7-10 days applied with as basal fertilizer rich in selenium, where the amount of basal fertilizer added is 20-30 kg/acre; (iv) planting cowpea in double row, spacing at 50-70 cm based on planting density, where the pore distance is 20-30 cm, and each pore has 1-2 plants, and watering; (v) carrying out field management by pumping to spread the fertilizer when the plants grow to height of 20-40 cm, inserting a bamboo pole, and placing frame to a height of 2-2.5 m, plugging deep into 15-20 cm/hole, slightly tilting inwards, intersecting every two bamboo poles, where the intersection of the upper discharge bamboo beams, showing herringbone, and spreading the seeds on shelves; and (vi) harvesting 10-15 days flowering of cowpea, allowing the cowpea seeds to grow in pods, expanding pod strip with uniform thickness, and full pod, with not real crisp white tissue softness, and not grain when exposed to swell during harvest period, taking out during early harvest once in every 4-5 days, mining once in every 1-2 days, taking out harvested seeds or dried beans, and allowing the brown pods, protecting the upper part of inflorescence flower while collecting without affecting the buds, and strain retained inflorescence, and choosing stalks together.