The invention discloses a biological moistening, moisturizing and drought-resistant organic fertilizer, aiming at solving the problem that the existing soil contains fertilizer but lacks water or contains the water but lacks the fertilizer. Raw materials of the fertilizer at least comprise sea tangle and seaweed. More specifically, the fertilizer comprises the following raw materials according toparts by weight: 1 part of white atractylodes rhizome, 1.5-2 parts of Chinese yam, 1.5-2 parts of taro, 6-7 parts of the sea tangle and 2.5-3 parts of the seaweed. In the organic fertilizer prepared from the raw materials, a water-absorbent material which is prepared from natural biomaterial can save more than 90% of water. The organic fertilizer has stronger hygroscopicity and once watering can provide soil with adequate moisture which is supplied to crops for growth by absorbing the moisture and nutrition, and ensure supplying the moisture to seeds or plant roots for a long time. The organic fertilizer has the advantages of being capable of adjusting soil moisture, improving soil salinity-alkalinity, having effects of moisturizing, disinfestation and weeding on the crops, being beneficial to crops growth, being beneficial to drought resistance and completely reducing the number of irrigations resulting from drought, greatly reducing manpower, irrigation works and electric power, andeffectively ensuring crop harvest. The organic fertilizer is an effective biological organic fertilizer.