A new type of γ ray detector array called Gammasphere with very perfect energy resolution is being constructed in Institute of Modern Physics. The Gammasphere in IMP will be composed of self-made CsI(Tl)crystals. In the first phase,one-sixth of the detectors had been finished from May 2009 to May 2010,including their processing and testing. This part consisted of 16 rings with 1024 pieces of CsI(Tl)crystal. All these CsI(Tl)crystals were wrapped in ESR and Aluminum Mylar. The non-uniformity of the light output and the energy resolution of CsI(Tl)crystal have been tested with the Hamamastu S8664-1010 avalanche photodiode(APD). The crystals was elaborately selected so that the light output A new type of γ ray detector array called Gammasphere with very perfect energy resolution is being constructed in Institute of Modern Physics. The Gammasphere in IMP will be composed of self-made CsI (Tl) crystals. In the first phase, one-sixth of the detectors had been finished from May 2009 to May 2010, including their processing and testing. This part consisted of 16 rings with 1024 pieces of CsI (Tl) crystal. All these CsI (Tl) crystals were wrapped in ESR and Aluminum Mylar. The non-uniformity of the light output and the energy resolution of CsI (Tl) crystal have been tested with the Hamamastu S8664-1010 avalanche photodiode (APD). The crystals was elaborately selected so that the light output