The invention discloses an H2S gas corrosion prevention cement slurry system for oil and gas well cementing. The H2S gas corrosion prevention cement slurry system is prepared from the following raw materials in parts by weight: 100 parts of cement, 0 part to 35.0 parts of silicon powder or quartz sand, 3.0 parts to 4.0 parts of an acid-resistance medium corrosion agent, 5.0 parts to 6.0 parts of corrosion resistant auxiliaries, 1.0 part to 2.0 parts of a dispersing agent, 3.0 parts to 4.0 parts of a filtrate loss reducer, 0.5 part to 3.0 parts of a retarding agent, 0.2 part to 0.3 part of an antifoaming agent, and 39.0 parts to 52.0 parts of water. Cement slurry provided by the system disclosed by the invention has good engineering performance, cement stones have good corrosion resistanceperformance under the conditions of high temperature and high concentration of H2S, a requirement that high H2S acidic gas reservoir cement stones are sealed for a long time is met, the ring sealing completeness of the cement and later-period safety of a well head are ensured, and effective technical guarantee is provided for exploitation and development.