The present invention relates to a polyhexamethyleneguanidine hydrochloride iodine medicine bath liquid and a preparation method thereof. The polyhexamethyleneguanidine hydrochloride iodine medicine bath liquid comprises the following components, by mass, 0.2-2 parts of iodine, 0.5-5 parts of potassium iodide, 0.1-1 part of potassium iodate, 0.1-1 part of sodium tripolyphosphate, 5-50 parts of polyhexamethyleneguanidine hydrochloride, 1-20 parts of a detergent, 0.5-5 parts of a skin care agent, 0.05-1 part of citric acid, and 15-92.55 parts of water. The preparation method comprises: respectively adding the polyhexamethyleneguanidine hydrochloride, the detergent and the skin care agent to the water, and stirring at a temperature of 45-70 DEG C until mixing is uniform; then adding the iodine, the potassium iodide, and the potassium iodate, and stirring at a temperature of 45-70 DEG C to completely dissolve; and adding the sodium tripolyphosphate and the citric acid, and stirring at a temperature of 45-70 DEG C until all components are completely dissolved to obtain the product. The medicine bath liquid of the present invention has characteristics of high effective iodine content, high sterilization effect and good stability, and is suitable for pastures. The preparation method of the present invention has a characteristic of simple operation, and can be applicable for large-scale production.