The Beijing Electron Positron Collider II (BEPCII) is a double-ring e+e- collider running in the tau-charm energy region (Ecm = 2.0-4.6 GeV), with a design luminosity of 1 × 1033 cm-2s-1 at the beam energy of 1.89 GeV, which had been achieved on April 5th 2016. The failure analysis system of the BEPCII has two subsystems to get the designated signals when the beam loss: the multiple channel recorder of the RF system and the beam loss diagnostic system based on the bunch by bunch beam position measurement. The causes behind the failure can be identified through the beam dynamics analysis. The failure analysis system can improve the reliability of the BEPCII. Two cases will be represented in this talk.