The Xiaoling (Xiao imperial tomb) of Emperor Wu of the Northern Zhou Dynasty was excavated by the Shaanxi Archaeological Institute in 1994. Because the coffin chamber had been broken into many times, many objects were damaged. In particular, many tiny organic objects were found making on-site excavation very difficult. In order to get all information, a method of embedding the objects in plaster was used on large scale. 73 plaster blocks were finished and transported to the lab, where lab-based mini-excavation was used. By this method, 2330 objects were unearthed, and many important objects and information which could not be found in the field work were revealed. Thus, lab-based mini-excavation method is become indispensible for archaeological excavation.