The invention discloses a raw material gas well mouth pressurization post-processing system and method. The system comprises a high-efficiency slug flow collecting system, a vertical gas-liquid separation system, a hydrocarbon pump system, an emergency drainage system, a monitoring system and a logic control system. According to control rules and design requirements of a slug flow collector and with combination of liquid level control characteristics of a gas-liquid separator, from the point of view of improving efficiency of slug flow collector and optimizing control of the system, a scheme for combination of the micro liquid accumulation plug flow collector and the vertical gas-liquid separator is put forward, the slug flow collecting capacity of the slug flow collector is reserved to the maximum extent, the process of an electric pump is optimized, the control level and gas-liquid uniformity of a downstream medium are improved, a rapid discharge function is achieved, and the adaptability of the system to large slug flow is expanded.