The China JinPing underground Laboratory （CJPL） is the deepest underground laboratory running in the world at present. In such a deep underground laboratory, the cosmic ray flux is a very important and necessary parameter for rare-event experiments. A plastic scintillator telescope system has been set up to measure the cosmic ray flux. The performance of the telescope system has been studied using the cosmic rays on the ground laboratory near the CJPL. Based on the underground experimental data taken from November 2010 to December 2011 in the CJPL, which has an effective live time of 171 days, the cosmic ray muon flux in the CJPL is measured to be （2.0±0.4）×10^-10/（cm2.s）. The ultra-low cosmic ray background guarantees an ideal environment for dark matter experiments at the CJPL.
Having advantages of low capacitance and low energy threshold, the PC-HPGe （Point-Contact High Furity Germanium） detector has found its application in the direct detection of WIMP（Weak Interaction Massive Particle） in CDEX （China Darkmatter Experiment）. The MSE （Multi-Site Event） and SSE（Single-Site Event） discrimination methods of the PC-HPGe detector are introduced in this article, including their physical basis, the electronics system and the algorithms to implement them. Behaviors of the PC-HPGe detector are studied intensively through this research and finally the experimental results of the LE discrimination method are presented.
