Abstract： Objective： To observe the clinical effect of paraffin therapy for soft tissue injury of grade Ⅰ based on AO classification and its effect on stress factors and pain factors. Methods：A total of 128 cases of patients with soft tissue injury of grade I based on AO classification were selected and divided into the observation group and the control group according to the random number table method， 64 cases in each group. The control group was given Qufeng Chenggu capsules and diclofenac sodium，and the observation group was additionally given paraffin therapy based on the treatment of the control group. Clinical symptom scores before and after treatment were compared in the two groups. Hemorheology indexes as well as levels of norepinephrine(NE)， angiotensin- 2(AT- Ⅱ)， superoxide dismutase(SOD)， 5- hydroxytryptamine(5- HT)， and substance P(SP) in serum were detected before and after treatment. Pain score and incidence of adverse reactions were observed. Results： After treatment， scores of swelling， tenderness， pain， ecchymosis， and dysfunction in the two groups were decreased when compared with those before treatment(P ＜0.05)； after treatment， the five scores in the observation group were lower than those in the control group(P ＜0.05). After treatment， plasma viscosity， whole blood viscosity at both high and low shear rates， and fibrinogen in the two groups were decreased when compared with those before treatment(P ＜0.05)；after treatment，the four indexes in the observation group were lower than those in the control group(P ＜0.05). After treatment，levels of NE and AT-Ⅱ in serum in the two groups were decreased when compared with those before treatment，and SOD levels were increased(P ＜0.05). After treatment，levels of NE and AT-Ⅱ in serum in the observation group were lower than those in the control group， and SOD level was higher than that in the control group(P ＜0.05). After treatment，levels of 5-HT and SP in serum as well as scores of Visual Analogue Scale(VAS) in the two groups were decreased when compared with those before treatment(P ＜0.05)；after treatment，the two levels in serum and the score in the observation group were lower than those in the control group(P ＜0.05). The incidence of adverse reactions was 4.69% in the observation group，and 1.56% in the control group，there being no significance in the difference(P ＞0.05). Conclusion：For patients with soft tissue injury of grade Ⅰ based on AO classification，paraffin therapy can promote local circulation of blood and lymph， improve clinical symptoms and hemorheology indexes， inhibit inflammatory response， relieve the body stress and pain，and reduce generation of pain factors，with safety and reliability.