Abstract：Objective：To observe the clinical effect of rectal instillation of Chushi Jiejing Prescription onⅢB type chronic prostatitis complicated by spastic constipation of puborectalis with syndrome of downward diffusion of dampheat. Methods： A total of 54 patients with Ⅲ B type chronic prostatitis complicated by spastic constipation of puborectalis with syndrome of downward diffusion of damp-heat treated in the Department of Andrology of Kaifeng Hospital of Traditional Chinese Medicine between January 2024 and April 2025 were selected and divided into the treatment group and the control group using the random number table method，with 27 cases in each group. During the study，one case was excluded from both groups. The treatment group was treated with rectal instillation of Chushi Jiejing Prescription， and the control group was treated with Tamsulosin Hydrochloride combined with Celecoxib. The two groups were treated for four weeks continuously. The clinical effects， and the scores of National Institutes of Health- Chronic Prostatitis Symptom Index （NIH-CPSI） and Longo-Obstructed Defecation Syndrome （Longo-ODS）， anal canal resting pressure，rectal defecation pressure，and traditional Chinese medicine syndrome scores before treatment and one week after treatment were compared between the two groups；the safety in both groups was evaluated. Results： The Mann-Whitney U test showed that the efficacy of the treatment group was better than that of the control group，the difference being significant （P＜0.05）. One week after treatment，the scores of NIH-CPSI and Longo-ODS in the two groups were decreased when compared with those before treatment， differences being significant （P＜0.05）， there being no significant differences between the two groups （P＞0.05）. One week after treatment， the anal canal resting pressure in the two groups was reduced when compared with that before treatment，and the anal canal resting pressure in the treatment group was lower than that in the control group， differences being significant （P＜0.05）. The rectal defecation pressure in the two groups was increased when compared with that before treatment，and the rectal defecation pressure in the treatment group was higher than that in the control group，differences being significant （P＜0.05）. One week after treatment， the scores of main symptoms， secondary symptoms and total scores of traditional Chinese medicine syndromes in the two groups were decreased when compared with those before treatment，and the above scores in the treatment group were lower than those in the control group，differences being significant （P＜0.05）. No obvious adverse reactions occurred in the two groups during the treatment. Conclusion：The rectal instillation of Chushi Jiejing Prescription can effectively mitigate the prostatitis symptoms and constipation of patients with Ⅲ B type chronic prostatitis complicated by spastic constipation of puborectalis with syndrome of downward diffusion of damp-heat， which is safe and reliable.