This paper introduces a laser amplifier with a non-uniform concentration of ceramic material as a laser gain medium. This gain medium structure prepared by ceramics is a circular thin-disk with a thickness of about 1mm and the size of the cross-section radius(r) is determined by the signal light to be amplified, the pump light absorption efficiency is generally above 96% and the uniformity of the pump light absorption distribution is a predetermined value, such as 96% or higher. The ceramic gain medium of this non-uniformly doped structure adopts a new way to achieve the uniformity of the gain distribution, this way resolves the contradiction between high absorption efficiency and high uniform gain, it is beneficial to realize high-power, high-efficiency and high-beam quality laser output.