The invention discloses an automatic tracking system of PH of a sulfonating and neutralizing system. The automatic tracking system comprises an sulfonic acid inlet, a caustic alkali liquor inlet is formed in the lower side of the sulfonic acid inlet, a production water inlet and a hydrogen peroxide inlet are formed in the lower side of the caustic alkali liquor inlet, a decelerant inlet is formedin the lower side of the hydrogen peroxide inlet, and the lower part of the decelerant inlet is connected with a buffer agent liquid level control tank. The automatic tracking system is adopted, alcohol ether sulfate from a SO3 sulfonating unit is metered accurately by a mass flowmeter and then enters a continuous neutralizing reaction mixing pump, and meanwhile neutralizing reaction reflux SLES enters the neutralizing reaction mixing pump. Liquid alkali is accurately metered by the mass flowmeter, the liquid alkali and the alcohol ether sulfate are automatically controlled to enter the neutralizing reaction pump according to the formula proportion, the adding amount is automatically controlled by a frequency converter of a micro-metering pump after the PH value is measured by a PH meter at an outlet of the mixing pump, and thus the accuracy of the liquid alkali quantity and the stability of the PH value of a product are achieved.