Abstract: Well S1 is a horizontal well deployed in an oil and gas field in East China Sea. The ϕ177.8 mm liner suspension cementing operation faced technical challenges such as susceptibility to liner hanger slippage, significant conflict between annular pressure stabilization and leak prevention, poor shoe track cementing quality, and inadequate bonding quality of thin cement sheaths. To ensure cementing safety and enhance the integrity of annular sealing integrity, targeted research and field applications have been conducted on optimization of supporting cementing processes. By optimizing the liner hanger setting process, adopting a dual-setting anti-gas channeling cement slurry system, injecting a high-viscosity pill to displace the cement slurry, optimizing centralizer placement to improve casing centrality, and utilizing a composite spacer fluid to clean the wellbore, the cementing operation was successfully completed. Post-cementing pressure testing met standards, and the cement top height reached the design requirements. The cementing quality meets the subsequent development requirements of the oil and gas wells. The construction technical approach and field application experience developed for this well provide technical reference for subsequent horizontal well liner suspension cementing in East China Sea oil and gas fields.