A device for detecting hydrolysis of titanium oxysulfate in real-time characterized in that it comprises: a detecting unit; and an analyzing unit, wherein the detecting unit is disposed in a solution contained in a hydrolysis container and is connected to the analyzing unit to detect a reflectance of the solution in real-time and transmit a detected result to the analyzing unit; and wherein the analyzing unit is configured to analyse a first derivative of the reflectance against hydrolysis time, and to determine that a change point of color to gray occurs when an inflection point of the first derivative occurs; and wherein the detecting unit comprises: a probe comprising a sealed cylinder, an opaque inner wall, a transparent window, a light source optical fiber, a detecting optical fiber, an interference filter sheet, and a chopper; and a light-emitting element, wherein the transparent window is disposed at an end of the cylinder; wherein the light source optical fiber and the detecting optical fiber are disposed in the cylinder and parallel to each other in a direction perpendicular to a plane on which the transparent window is positioned; wherein the interference filter sheet is fixed at front ends of the light source optical fiber and the detecting optical fiber in a direction parallel to the plane on which the transparent window is positioned; and wherein the chopper through which only incident light passes is interposed between the interference filter sheet and the transparent window, and is positioned only in front of the light source optical fiber. a detecting unit; and an analyzing unit, wherein the detecting unit is disposed in a solution contained in a hydrolysis container and is connected to the analyzing unit to detect a reflectance of the solution in real-time and transmit a detected result to the analyzing unit; and wherein the analyzing unit is configured to analyse a first derivative of the reflectance against hydrolysis time, and to determine that a change point of color to gray occurs when an inflection point of the first derivative occurs; and wherein the detecting unit comprises: a probe comprising a sealed cylinder, an opaque inner wall, a transparent window, a light source optical fiber, a detecting optical fiber, an interference filter sheet, and a chopper; and a light-emitting element, wherein the transparent window is disposed at an end of the cylinder; wherein the light source optical fiber and the detecting optical fiber are disposed in the cylinder and parallel to each other in a direction perpendicular to a plane on which the transparent window is positioned; wherein the interference filter sheet is fixed at front ends of the light source optical fiber and the detecting optical fiber in a direction parallel to the plane on which the transparent window is positioned; and wherein the chopper through which only incident light passes is interposed between the interference filter sheet and the transparent window, and is positioned only in front of the light source optical fiber. a probe comprising a sealed cylinder, an opaque inner wall, a transparent window, a light source optical fiber, a detecting optical fiber, an interference filter sheet, and a chopper; and a light-emitting element, wherein the transparent window is disposed at an end of the cylinder; wherein the light source optical fiber and the detecting optical fiber are disposed in the cylinder and parallel to each other in a direction perpendicular to a plane on which the transparent window is positioned; wherein the interference filter sheet is fixed at front ends of the light source optical fiber and the detecting optical fiber in a direction parallel to the plane on which the transparent window is positioned; and wherein the chopper through which only incident light passes is interposed between the interference filter sheet and the transparent window, and is positioned only in front of the light source optical fiber.