A thoracic arch spring teaching aid, comprising a thoracic arch spring (1) having a contour similar to that of the sternum of the human body. The thoracic arch spring (1) has an area enclosed therein as a simulated thoracic cavity (100); the thoracic arch spring (1) comprises a plurality of arch-shaped spring pieces (11); limit spring plates (21, 22) for pressing the spring pieces (11) are provided above and/or below the thoracic arch spring (1); the limit spring plates (21, 22) comprise base portions (210, 220) contacting the spring pieces (11) and extension portions (211, 221, 211′, 221′) located at two sides of the base portions (210, 220); the extension portions (211, 221, 211′, 221′) extend along the projections of the spring pieces (11) on the plane where the base portions (210, 220) are located. The teaching aid can prevent the spring pieces (11) from forming a shearing force region when the spring pieces (11) are pressed; thus, deformation or breakage is avoided, and the service life is prolonged.