A hydraulic hinge for a glass door, characterized in that the hydraulic hinge comprises: a fixing plate; a base combined with the fixing plate and having a top side; a bottom side; a front side; a rear side; a right side; a left side; a longitudinal direction defined from the top side to the bottom side; a lateral direction defined from the front side to the rear side; a first space formed in the base along the longitudinal direction; a second space formed in the base along the lateral direction and communicating with the first space; an oil passage formed in the base and communicating with the first space and the second space and having a first passage formed in the base and communicating with the first space; a second passage formed in the base and communicating with the first passage and the second space; an adjusting hole formed in the base and communicating with the first passage and the second passage;an adjusting unit moveably mounted in the adjusting hole; and a pivot rotatably mounted in the first space and having a side; an abutted surface formed in the pivot; and an adjusting space formed in the side of the pivot and adjacent to the abutted surface and communicating with the first passage of the oil passage; a buffer module mounted in the second space and having a fixed cover mounted in and sealing the second space and adjacent to the fixing plate; a sliding tube slidably mounted in the second space and abutting the pivot and having an end abutting the pivot; an assembling portion formed in the end of the sliding tube, the assembling portion abutting the pivot and selectively communicating between the second space and the adjusting space; a spring mounted between and abutting the fixed cover and the sliding tube; and a clamping module pivotally mounted on the pivot and having two clamping plates pivotally mounted on the right side and the left side of the base respectively; characterised in that the adjusting hole is formed in one of the right side and the left side of the base. a fixing plate; a base combined with the fixing plate and having a top side; a bottom side; a front side; a rear side; a right side; a left side; a longitudinal direction defined from the top side to the bottom side; a lateral direction defined from the front side to the rear side; a first space formed in the base along the longitudinal direction; a second space formed in the base along the lateral direction and communicating with the first space; an oil passage formed in the base and communicating with the first space and the second space and having a first passage formed in the base and communicating with the first space; a second passage formed in the base and communicating with the first passage and the second space; an adjusting hole formed in the base and communicating with the first passage and the second passage;an adjusting unit moveably mounted in the adjusting hole; and a pivot rotatably mounted in the first space and having a side; an abutted surface formed in the pivot; and an adjusting space formed in the side of the pivot and adjacent to the abutted surface and communicating with the first passage of the oil passage; a buffer module mounted in the second space and having a fixed cover mounted in and sealing the second space and adjacent to the fixing plate; a sliding tube slidably mounted in the second space and abutting the pivot and having an end abutting the pivot; an assembling portion formed in the end of the sliding tube, the assembling portion abutting the pivot and selectively communicating between the second space and the adjusting space; a spring mounted between and abutting the fixed cover and the sliding tube; and a clamping module pivotally mounted on the pivot and having two clamping plates pivotally mounted on the right side and the left side of the base respectively;