Using the Otect Gem 30 gamma spectrometer specified by high resolution, using 83cm3 Ge ultrapure Detector (Ultra-pure detector), situated in the lead-plated background-reduced house, resolution of 1.82 KeV, energy of 1332 KeV of the 60CO. The equipment can quantify most of the radio nuclides in the environment. Especially, this device can determine the concentration of 238U by computing 234Th isotope at 63,29 KeV energy photopeak that the pre-existing equipment can not solve' this problem. This article introduces the ability of quantitative analysis of radioactive isotopes for environmental samples by spectrometer.