The invention discloses a low-temperature cured terminal carboxyl polyester resin for mixed powder coating. The polyester resin is prepared by performing melt polycondensation reaction on the following components in percentage by weight: 25 to 45 percent of polyalcohol, 35 to 65 percent of aromatic polyatomic acid, 0 to 10 percent of fat polyatomic acid, 0 to 2 percent of branching agent, 6 to 15 percent of acid hydrolysis agent, and 0.01 to 0.15 percent of esterification catalyst. The invention also discloses a method for preparing the low-temperature cured terminal carboxyl polyester resin. The prepared polyester resin has the characteristics of proper glass-transition temperature, softening point, good storage stability, and the like; the polyester resin, epoxy resin, filler and assistant in a certain proportion are mixed, and the mixture is prepared into powder through melt extrusion mixing, cooling, crushing and sieving; and the prepared powder can be cured at the temperature of 160 DEG C, and has the advantages of excellent leveling performance, good impact performance, and the like.