The invention discloses a pH (potential of hydrogen) fluorescence probe on the basis of 2-(2'-hydroxycyclohexyl phenyl ketone) benzothiazole derivatives, a method for preparing the pH fluorescence probe and application thereof. R groups are directly connected with 2-(2'-hydroxycyclohexyl phenyl ketone) benzothiazole parent bodies or are connected with the 2-(2'-hydroxycyclohexyl phenyl ketone) benzothiazole parent bodies by benzene rings to obtain the pH fluorescence probe on the basis of the 2-(2'-hydroxycyclohexyl phenyl ketone) benzothiazole derivatives; the R groups are pyridyl, thienyl, quinolyl, furyl, pyrimidine heterocycle aromatic groups, hydroxyl, methyl, methoxy, carboxyl or sulfonyl. The pH fluorescence probe, the method and the application have the advantages that ratiometric fluorescence response can be carried out, wavelengths of two fluorescence channels are greatly different from one another, accordingly, the fluorescence channels are free of interference on one another during detection, and fluorescence signalization can be easily observed by naked eyes; the pH fluorescence probe is high in Stokes shift, and accordingly influence on detection due to excitation light sources can be effectively prevented; the pH fluorescence probe is high in pH response sensitivity, the titration end point of the pH fluorescence probe can be within the ranges from weakly acidic ranges to weakly alkaline ranges under the control, and the pH fluorescence probe is quite suitable for detecting subtle pH change of life samples and food samples; the pH fluorescence probe is high in anti-interference capacity.