The invention discloses a composite sand core for metal mold casting and a preparation method of the composite sand core for the metal mold casting. The preparation method of the composite sand core for the metal mold casting comprises the steps that firstly, a heat-resistant core head is manufactured from ceramic materials or heat-resistant sand blocks; the core head is placed at a corresponding position in a core box; core sand obtained through even mixing of sand, water and an additive is placed in the core box and compacted; and finally, freezing is conducted, and then the composite sand core is obtained. By the adoption of the composite sand core for the metal mold casting and the preparation method of the composite sand core for the metal mold casting, heat transmitted by a high-temperature metal mold to a frozen sand core body can be greatly reduced, the frozen sand core placed in the metal mold can maintain high strength for certain time, so that metal mold casting technological requirements are met, and it is possible that the environment-friendly excellent-performance frozen sand core can be applied to metal mold gravity casting, low-pressure casting and the like.