The Chinese Fusion Engineering Test Reactor (CFETR) is the next-generation fusion device of China for realization of fusion energy. Its mission aims to bridge the gaps between the International Thermonuclear Experimental Reactor and the demonstration reactor. To perform the maintenance work on the CFETR, remote handling systems shall be equipped on the device. To inspect and identify the status and position of the in-vessel components of CFETR, a remotely operated in-vessel viewing system (IVVS) shall be used. Such an IVVS prototype with articulated arm and viewing system has been built in China. Its dimension bases on the size of Experimental Advanced Superconducting Tokamak (EAST) due to similar shape of the reactor and the limited project budget. To assemble and store the IVVS around the Tokamak, a cylindrical vacuum vessel with foundation support inside is designed and checked. To isolate the vacuum of the vessel from the vacuum of Tokamak, an ultrahigh vacuum gate valve with a bellow is installed between them. To maintain the vacuum degree of the Tokamak after its connection with the vessel, a set of vacuum unit with molecular pump is configured for the vessel. Before integration testing on the EAST, some performance tests of the IVVS are carried out on the remote handling test facility and in other laboratories. The test results show that it is feasible to apply such an IVVS concept to the CFETR.