To observe the therapeutic effect of acupuncture and mild moxibustion on chronic prostatitis and to probe into the mechanism of the therapy. Two hundred patients with chronic prostatitis were randomly divided into two groups so as to observe respectively the changes in clinical symptoms, count of WBC and lecithin corpuscles in succus prostaticus, prostatic capcules and internal echo, tenderness and elasticity of prostate by palpation before and after treatment. After treatment, a remarkable improvement was found in clinical symptoms, succus prostaticus test and ultrasonic examination in the treatment group with a statistically significant difference (P < 0.05) as compared to the control group. The treatment of chronic prostatitis with acupuncture and mild moxibustion can remove the stagnation of succus prostaticus, improve the blood circulation in prostate, inhibit or kill the pathogenic micro-organisms, strengthen or regulate the immune function of the patients, improve local blood circulation, eliminate the accumulation of secretion and relieve the obstruction of the prostatic ducts.