The invention discloses a method for improving sludge anaerobic fermentation and acid production, belonging to the environmental protection technical field. The method is taken as follows: the residual sludge of municipal sewage plants are used as the raw material, wall breaking action is applied to the microorganisms in the sludge by control of the operating parameters of ultrasonic in order to ensure most of the organic substances in the cells of the microorganisms to be dissolved, lye is added to the sludge to regulate the pH value of the sludge, and the sludge is transformed furthest from the solid phase to the liquid phase and made to produce volatile organic matter under the action of the lye and the microorganisms. The invention further improves the quantity of the organic acid produced from the sludge on the basis of sludge innoxiousness and resource utilization.