A
pH measurement system, comprising: a liquid intake
pipe for a liquid to be measured, a flushing
pipe, a
pH measurement water tank (2) and a protective-
liquid water tank (11), wherein the protective-
liquid water tank (11) is configured to store a protective liquid; an output end of the liquid intake
pipe for the liquid to be measured and an output end of the flushing pipe are connected to the
pH measurement water tank (2); a flow
measurement device is provided on the liquid intake pipe for the liquid to be measured; an output end of the protective-
liquid water tank (11) is connected to the pH measurement water tank (2) by means of an output pipe of the protective-liquid water tank; a pH
measurement device is provided inside the pH measurement water tank (2), a
liquid level measurement device is provided on a side wall of the pH measurement water tank (2), and a liquid
discharge pipe is provided at the bottom of the pH measurement water tank (2); and a first electric valve (13) is mounted on the output pipe of the protective-liquid water tank, and a second electric valve (10) is mounted on the liquid
discharge pipe. The pH measurement
system enables the protective-liquid water tank (11) to inject the protective liquid into the pH measurement water tank (2) in a deactivated state on the basis of feedback from the
liquid level measurement device and the flow
measurement device, thereby achieving offline protection of the pH measurement device.