Objective: To explore the area and sensitization variance of acupoint when internal organs is under pathological condition. To observe quantity-effect variance of subnucleus reticularis dorsalis to electro-acupuncture under both physiological and pathological condition. To explain medulla oblongata mechanism of acupoint sensitization. Method: Mustard oil (20μl，2.5% Sigma-Aldrich, St.Louis, MO) was imported into colon and rectum of male SD rats (anaesthetised with pentobarbital sodium 50-60mg.kg-1) in order to observe its influence to acupoint sensitization. SRD Neuron activities were recorded. Visceral nociceptive stimulus was generated by colorectal distension (CRD with an intensity 40 mmHg). Quantity-effect variance of neuron activity to electroacupuncture to “Zusanli-Shangjuxu” area both before and after CRD was observed. Result: Visceral inflammation could facilitate SRD neuron activity to acupoint stimulation. Visceral nociceptive afference could enhance neuron activity to acupoint acupuncture. WDR neuron activity caused by electro-acupuncture increased when visceral nociception is raised. Conclusion: the area of acupoint could be changed if visceral function changes, also, sensitivity of acupoint would change too. Key words: Sensitization of acupoints, Neurogenic inflammatory reaction, subnucleus reticularis dorsalis, colorectal distension (CRD)