The invention relates to a protection and rejuvenation method for the tree body of an ancient tree. The method comprises the following steps: 1) debridement of the trunk: cleaning the pollutants attached to the trunk by using a physical cleaning mode, wherein the cleaning is carried out in time after raining, or after soaking the trunk with water in a long-term drought condition; 2) prevention andcontrol of scale insects: carrying out the prevention and control of the scale insects by using a physical cleaning mode; 3) rejuvenation treatment of the root system: carrying out rejuvenation treatment on the root system through burying perfusion tubes between the roots and pouring plant rooting hormone by stages. According to the invention, a physical mode is mainly used to carry out the debridement of the trunk and the prevention and control of the scale insects, the prevention and control method is clean, the secondary harm to the tree body of an ancient crape myrtle tree is not caused,and a series of pollution problems caused by chemical methods on the tree body and surrounding environment of the ancient crape myrtle tree are avoided; furthermore, the plant rooting hormone is usedfor the rejuvenation treatment of the root system, so that the growth of the root system is good in growth, the absorption of nutrient substances is further ensured, and the survival life of the ancient crape myrtle tree is prolonged.