The invention discloses a prefabricated segmental assembling concrete bridge pier and a connection technique thereof. A lower threaded steel rod is pre-buried in the lower portion of a pier body section. An upper threaded steel rod is pre-buried in the upper portion of the pier body section. The lower portion of a threaded sleeve serves as a threaded section. The upper section of the threaded section is connected with a connection section. The upper portion of the connection section is connected with a sleeve body. The threaded section of the threaded sleeve is connected with the lower threaded steel rod. The upper threaded steel rod is inserted into the threaded sleeve from the top. The threaded sleeve is sleeved with a cylindrical notch. The lower threaded steel rod, the upper threaded steel rod, the threaded sleeve and the cylindrical notch are fixedly connected through cement mortar. The grout sleeve is divided into the upper part and the lower part. The pier body section can be hoisted directly by screwing the lower half part, namely the detachable threaded sleeve, on site, and the workload is small. The diameter of the cylindrical notch is twice the diameter of the top of the detachable sleeve, the diameter of the top of the detachable sleeve is three times the diameter of the pre-buried threaded steel rod, the construction permissible error is large, the construction efficiency is high, the difficulty is low, and operation is easy.