A brake caliper structure of a straddle seat off-load vehicle includes a brake caliper having a caliper bracket, a caliper assembly connected to the caliper bracket by two connecting portions so that the caliper assembly can move relative to the caliper bracket to clamp a brake disc. One connecting portion includes a slide pin connected to the caliper assembly and slidably received in a guide hole in the caliper bracket for effectively guiding movement of the caliper assembly relative to the caliper bracket, and the other connecting portion includes a connecting screw as a fixed pin secured to the caliper bracket, and a rubber bushing as an elastic member disposed between the caliper assembly and the fixed pin for taking up the tilting of the brake disc.