The inventor of Moist Exposed burn Therapy- professor Rongxiang Xu divides the degree of the skin heat injury into "three degree six types" scientifically, which is abbreviated as Three Degree Six Division.

And also this kind of "Three Degree Six Division" is used as the diagnostic code for the classification of the damage depth of the burn wound by the Committee of Burns of the Chinese Academy of the Combination of Traditional Chinese Medicine with Western Medicine, which is: First degree, superficial second degree, deep second superficial type, deep second deep type, superficial third degree and deep third degree.

2. II-degree burns can be divided into three grades: 

(1) Superficial second-degree type: refers to burn injury reaching the basal layer of epidermis with some of the basal layer still surviving. 

(2) Superficial deep second-degree type: refers to burn injury reaching the dermal papillary layer while deep second-degree deep burns refers to burn injury reaching the dermal reticu-lar layer. The theoretical basis is that in superficial second-degree burns wounds, the skin microcirculation has been injured but there is no stasis zone and most of the skin structure is retained. 

(3) Deep second-degree deep type, the stasis zone occurs in the dermal papillary layer but epidermal structure is lost while most of the skin appendages are still retained. In deep second-degree deep burns wounds, a microcirculation stasis zone is formed in the dermal reticular layer and only a small part of the appendages is retained.

3. III-degree burns can be divided into two grades.

(1) Superficial third-degree burns: The full-thickness skin is injured and the injury reaches the superficial layer of the subcutaneous fatty tissue.

(2) Third-degree burns:  The full-thickness skin is injured and the injury reaches the deep layer of the subcutaneous fatty tissue.

In clinical practice, people often find that some burns wounds contain an obvious granulation while, around the lesion, there are a few scattered skin island tissues. This is called mixed-degree burn.