This paper describes the emission spectrum characters of Er ∶ YAG crystal. Two sets of laser devices are designed& one is single flash tube with single ellipsoidal condenser cavity, the other is double flash tube with double ellipsoidal condenser cavity and its power supply. 概述了Er∶YAG晶体的光谱特性,在此基础上设计研制了2套激光装置,单灯单椭圆和双灯双椭圆聚光腔及电源,比较了两者的优缺点。