We study the Bell inequality in a holographic model of a casually disconnected Einstein-Podolsky-Rosen (EPR) pair. The CHSH form of Bell inequality are computed using holographic Schwinger-Keldysh(SK) correlators. We show that the manifestation of quantum entanglement in Bell inequality can be reproduced from the classical gravitation theory in the bulk, which lends support to the ER=EPR conjecture.