There are many reasons for the decline of human immunity: first, the decline of human immunity may be caused by endocrine disorders, which can easily cause abnormal secretion of hormones in the human body, leading to the emergence of various adverse diseases and causing the decline of human immunity. Secondly, it may also be caused by plant nerve dysfunction, which can cause the human immunity and resistance to decline, and appear weakness, excessive sweating, reduced attention span, memory loss. Then, it may be caused by certain undesirable diseases, such as diabetes and thyroid disease, which can cause damage to certain functions of the human body and cause a decrease in human immunity and the appearance of weakness, excessive sweating, fear of heat, and dry mouth.