In order to attract more support from both domestic and international support for the electron-ion colliderin China (EicC), we will schedule one fourth (the 1st and 2nd of the electron-ion colliderin China (EicC) meetings were hosted at IMP, Lanzhou, while the 3rd one was hosted at Duke Kunshan University, Kunshan, Jiangsu province. See more details from: https://indico.ihep.ac.cn/event/8751/ ) of our meetings in Tsuinghua University, Beijing. During this meeting, we invite world experts on the physics and accelerator of the polarized electron-ion collider to discussion the issuesrelated to the accelerator design and physics potentials. Physics goals, results of the detector simulations, design and the most recent accelerator designs will be discussed.