The invention discloses a preparation method of a gynura segetum extract and a preparation method and application of a gynura segetum composite preparation for treating and preventing livestock and poultry hemorrhagic diseases. Particularly, traditional Chinese medicine of gynura segetum or extracts of the gynura segetum are proportionally compounded with glucose oxidase and the like to prepare the composite preparation for treating and preventing the livestock and poultry hemorrhagic diseases. The composite preparation comprises a premixed preparation, oral liquid and soluble compounds. A product is mainly used for treating and preventing the livestock and poultry hemorrhagic diseases; the prepared composite preparation has the characteristics that the stability is high; the effect is obvious; the cost is low; the scaled production is easy; the use is convenient, and the like. The composite preparation can partially replace or totally replace antibiotics and can be widely applied to the prevention of livestock and poultry diseases; the livestock and poultry feed utilization rate and the disease resistant capability can be improved.