Abstract: A Large Ion Collider Experiment(ALICE) at the Large Hadron Collider(LHC) at CERN will undergo a major upgrade during the 2nd LHC Long Shutdown(LS2) scheduled in 2019~2021 that will allow to study in detail of strong interaction matter Quark-Gluon Plasma(QGP) properties. To collecting more Pb-Pb events during the Run 3 and Run 4, the replacement of the existing Inner Tracking System(ITS) with a completely new ultra-light high resolution detector based on Monolithic Active Pixel Sensors(MAPS) technique is one of the cornerstones within this upgrade program. The new ITS will consist of seven detection layers: 3 inner layers, 2 middle layers and 2 outer layers. The upgraded ITS will be realized using more than twenty-four thousand pixel chips (called ALPIDE) covering a total active surface of about ten square meters. The thickness of ALPIDE is 50 μm, also with a pixel pitch of 27 μm × 29 μm. The main features of the ALPIDE are of low power consumption, high resolution and high speed readout. ITS2 will enable the ALICE detector to have excellent detection efficiency and impact parameter resolution when measuring extremely low transverse momentum particles, and also make the ALICE detector suitable for LHC high luminosity environment. At present, the production and test of the detector module of ITS2 project have been completed, and the integration of 7-layer barrel been completed at CERN clean room, and the on-surface commissioning has been completed in the end of 2020. The installation plan of ITS2 at the ALICE detector has been started in Jan. 2021, and is scheduled to be finished in end of May 2021. This talk will focus on the design and the physics performance of the new ITS, as well as the advanced techniques adopted in detector assembly and integration will be introduced. The status and commissioning of the ITS upgrade project will be reported.