Large-caliber　water　meter　shells　are　prone　to　shrinkage　porosity,　wrinkles,　air　entrapment,　slag　inclusion,　and　other　defects　during　the　lost　foam　casting　process.　Taking　the　vertical　spiral　wing　WS-100　water　meter　as　the　research　object,　through　the　analysis　of　the　structure　of　the　water　meter　shell,　the　flow　field　and　temperature　field　of　the　design　of　outer　bottom　injection-vertical　pouring,　outer　bottom　injection-horizontal　pouring　and　inner　bottom　injection-horizontal　pouring　involved　in　the　filling　and　solidification　process　are　numerically　simulated　and　solve　analysis,　respectively.　The　results　showed　that:　when　the　inner　bottom　injection-horizontal　pouring　process　was　adopted,　the　filling　process　of　the　casting　was　stable,　the　isolated　liquid　phase　area　of　the　solidification　process　was　relatively　small,　and　the　possibility　of　forming　defects　was　less.　The　casting　performance　is　excellent,　and　the　numerical　analysis　is　verified　to　be　effective.