Polypeptide, a titanium nutrient solution, a rare earth nutrient solution, amino acid, trace elements and the like are firstly adopted to prepare a multifunctional biological fertilizer capable of adjusting the growth of forage grass and improving bacteria-resisting, virus-resisting, pest-expelling and pest-killing capacities of the forage grass and used for production of the forage grass, and a high-quality product is provided for returning grazing land to grassland and restoring grassland vegetation in China. The special fertilizer provided by the invention can induce the development of a root system of the forage grass and the germination of forage grass leaf buds, improves the germination rate of forage grass seeds, induces the sensitivity of the forage grass to photosynthesis, reinforces the expelling and killing capacities of the forage grass to diseases and pests, improves the adaptive capacity of the forage grass to an inverse environment, and improves the yield and the qualityof the forage grass per unit area. The special fertilizer has the advantages of convenience in usage, simple method, low cost, and intuitional and significant yield-increasing effects. Test results for two consecutive years by the Qinghai Grassland Station and the Qinghai Sanjiangyuan Ecology Protection and Construction Office show that the yield of the forage grass can be improved by about 25% through application of the special fertilizer.