Abstract: The authors explain why the SHRIMP, as an in-situ microanalysis machine, was invented by scientists more than twenty years ago. It is introduced that what thought was come into being in designing for the first SHRIMP, that the hardship course the inventors had experienced for making the machine, and that the properties SHRIMP possesses. The contributions of SHRIMP to Earth Sciences, especially to zircon isotope geochronology, are also shown.