Dermatomyositis is an autoimmune disease that affects the skin and skeletal muscles. The clinical manifestations are mainly rash, muscle weakness, and myalgia. In the early stages of this disease, external pathogens enter the interior, transforming heat into toxins. The toxins accumulate in the skin, leading to rash; Subsequently, heat toxicity, dampness, and blood stasis are intertwined, leading to an exacerbation of the rash and burning pain in the joint muscles; Long term illness with deficiency of Qi, blood, Yin and Yang, resulting in muscle soreness, limb weakness and Professor Tang Xiaohu summarized based on years of clinical experience that in the acute phase, heat toxicity is the main pathagen, and the treatment should focus on clearing heat and detoxifying, promoting blood circulation and relieving pain. If the heat toxin is trapped in the heart camp, the treatment is to clear the camp, detoxify, and nourish Yin through heat. For those with a heavy emphasis on blood stasis and heat, the treatment should be to promote blood circulation and remove blood stasis, regulate Qi and strengthen the spleen. For those who are more prone to dampness and heat during the remission period, the treatment should be to clear heat, promote dampness, and promote the circulation of meridians. In the chronic stage, patients with deficiency of both Qi and blood are mainly treated with nourishing Qi, warming meridians, nourishing blood, and collaterals. For those who mainly suffer from Yin deficiency, the treatment is to nourish the liver and kidneys, nourish Qi and nourish Yin. For those with Yang deficiency as the main treatment, it is recommended to warm the Yang and unblock the meridians, strengthen the spleen and benefit the kidneys. At the time of clinical diagnosis, professor Tang Xiaohu identified pathological factors and used precise medication. This article takes the example of acute heat toxicity and invagination of the heart as an example, and elaborates on the combination of Qingying Tang and Qinghao biejia Tang with modifications.