The invention discloses a synthetic resin composite for pouring middle-voltage bus bar, which is composed of epoxy resin, curing agent and quartz sand, wherein the composite comprises the epoxy resin and the curing agent in percentage by weight: 45-50% of epoxy resin and 12-20% of curing agent; the grain diameter of quartz sand is 2-150 meshes, wherein the composite comprises the quartz sand in percentage by weight: 6-11% of quartz sand with the grain diameter being more than or equal to 2 meshes and less than or equal to 10 meshes,10-15% of quartz sand with the grain diameter being more than10 meshes and less than or equal to 50 meshes, 6-11% of quartz sand with the grain diameter being more than 50 meshes and less than or equal to 80 meshes, and 6-10% of quartz sand with the grain diameter being more than 80 meshes and less than or equal to 150 meshes. The composite can pour out of a bus bar copper conductor to cure and form an insulating layer, has favourable impact resistance andsmall internal stress and has small possibility of cracking and dropping. The prepared bus bar can be used in a middle-voltage distribution system of 3-17.5kV.