||High refractive index polymers (HRIPs) which have refractive index exceeding 1.6, have a many attention due to variety of optoelectronic devices such as optical waveguides, image sensors, lithography, and light-emitting diodes. However, up to date, the HRIPs exceeding 1.8 is still rare, and HRIPs with maintaining full transparency in the visible range have remained challenging. Herein, our groups develop a novel one-step vapor-phase process, termed sulfur chemical vapor deposition, to synthesize successfully ultrahigh refractive index (n ＞ 1.9) polymers directly from elemental sulfur. Notably, the HRIP thin film showed unprecedented optical transparency (＞90%) in the visible range, attributed to suppress the formation of long polysulfide segments within the SCPs. The colorless organic film with high refractive index will will serve as a key component in a wide range of optoelectronic device.