The interaction of neutrino and matter can produce charged particles. By detecting the Cherenkov light generated by these charged particles the neutrinos can be observed. We propose a cubic-kilometer scale high-energy neutrino detector located in the South China Sea, Neutrino Observatory in the Nanhai (NEON). The detector will use tens of thousands of optical modules (OMs), in which multiple photomultipliers tubes (PMTs) are housed in a transparent glass sphere. To get the optimum performance, these PMTs should have homogeneous photocathode response. In this work, we test the response of PMTs under different lighting angles, obtaining the collection efficiency of individual PMTs. Finally, the mechanical structure of the module is designed and tested for shockproof packaging during transportation. In addition, we designed two types of robotic arms to improve the efficiency of measuring the optical properties of PMT and OM.