To counter the drilling technology, bore well structure and mud system, Casson rheology pattern was optimized and circulation Pressure Drop of CCSD-1 well in different depth was calculated by applying mathematical statistics andregression analysis with 2000m cored drilling practice and data collection of drilling fluid performance testing. Circulation Pressure Drop of PDM and Hydro-percussive hammer for rotary-type double tube core barrel tool were respectively tested. Pressure loss distribution of circulation fluid in each pipe passage was decided in conclusion.