A process optimization has been applied on an existing oil absorption, propane pre-cooling and J-T valve throttling refrigeration process to upgrade the capacity of an overseas light hydrocarbon recovery plant to 2.83 million m3/d (100MMSCFD), and meet the requirement of C3recovery rate ≥ 95%, C4recovery rate ≥ 98.5%,while utilizing parts of the equipment and facilities of existing plant.Compared with DHX process for light hydrocarbon recovery, a DHX process with propane refrigeration, expander refrigeration and deethanizer overhead gas condensation and reflux was selected.This process realizes two-step cooling of the overhead gas of the deethanizer,and effectively improves the C3recovery rate.After process optimization, the C3recovery rate of the light hydrocarbon recovery plant was increased from the 60.1% to 95.5%,C4recovery rate was increased from the 61.3% to 99.7%,LPG production rate improved to 210t/d,with increasing approximately 130t/d. The design value requirements have been met, and the economic benefits have been significantly improved.The process is a good reference for the design and optimization of similar projects.