Well PZ103 H is a typical ultra-deep well of marine carbonate in western Sichuan, with a buried depth of 6071 m and temperature of 155℃. To solve the problem that the ultra-deep and tight reservoir may not be fractured, the design is to replace acid to the production layer as much as possible, and use 140 MPa wellhead and corresponding high pressure manifold. In view of the risk of acid corroding tube during shock extrusion test, the formulation of high-temperature corrosion inhibitor was optimized. The corrosion of P110SS tube was only 21 . 4 g /(m2· h) , far less than the industrial standard requirement of 100 g /(m2· h) under the condition of 180℃ and 24 h in the laboratory. The combination tool of “mechanical packer ( RTTS) + hydraulic packer (Y241) ” was designed to carry out staged acid fracturing because the reservoir section was 83 m and it was difficult to distribute acid evenly. At the same time, in order to achieve deep acid fracturing, a large-scale acid fracturing with a total liquid volume of 2 132 m3 in two stages was designed by alternating injection of three liquids of “gelling acid, crosslinked acid and fracturing fluid”. Field application shows that the designed combination tool meets the requirements of staged and large-scale ultra-high pressure operation. After acid fracturing, the gas production is 12. 65 × 104 m3 /d and water production is 276 m3 /d under tubing pressure of 14. 2 MPa, which fully evaluates the reservoir. Formed by the combination of high temperature corrosion inhibition acid, ultra-high pressure construction, “mechanical packer (RTTS) + hydraulic packer (Y241) ” tools and multi-stage alternating injection, the technology of staged acid pressing provides reference for similar ultra-deep and high-sulfur reservoirs.