The invention discloses a multifunctional purification device and a purification method, and belongs to the technical field of produced gas purification. The multifunctional purification device comprises a U-shaped hollow cylinder with a top opening. A top cover is detachably mounted on the top of the cylinder. A gas outlet is formed in the upper portion of the cylinder. A gas-liquid phase inlet is formed in the lower portion of the cylinder. A separation water outlet is formed in the bottom of the cylinder. A separation partition plate set and a purifier core are detachably arranged in the cylinder. Produced gas-liquid phase enters the cylinder from the gas-liquid phase inlet and is sequentially subjected to gas-liquid phase separation through the separation partition plate set, and afterpurification through the purifier core, gas phase is output through the gas outlet. The purification device is integrated with sand removing, water removing, separation and purification, has the characteristics of being good in purification effect, convenient to dismantle, easy to clean, resistant to corrosion and the like, and plays an important role in gas transmission pipelines.