Abstract: One set of multi-shot'in-situ’pellet injection system,with the maximum capacity of 8 pellets during one discharge,has been constructed in the Institute of Plasma Physics,Chinese Academy of Sciences.It has been operated on HT-7 tokamak,the lst superconductive tokamak in China,and HT-6M for the single and multi-shot pellet injection experiments.Its differential section and control unit are proved to be convenient and reliable.The velocity and dimension of the pellets are measured.During the experiments,significant and typical phenomena are observed.Deep fueling is obtained.The line average eletron density in the center is increased by one half in the single pellet injection,and for 100%in the 2-pellet injection.The hollow electron temperature profile is also observed.In this paper,the structure and the operation of the multi-shot pellet injection system are introduced.Some experimental results are provided and the simple physical analysis are given.