In order to simulataneously achieve surface type conversion and sulfur passivation of p-type InP, a Ha$_{2}$S plasma dry passivation technique was firstly proposed and successfully applied to the fabrication of ITO/InP solar cells. This new technique was expected to improve the performance of solar cells. The devices, fabricated by changing the process parameters such as RF power and plasma exposure time, were characterized and PL measurements were performed to investigate the passivation effects. As a result, H$_{2}$S plasma treated solar cells demonstrated better performance than that of (NH$_{4}$)$_{2}$S$_{x}$ treated ones.s.