Pore structural parameters of 2 kinds of alumina before and after modification were reported, and with the modified alumina as coating Pd-based catalysts were prepared. The results show that the modified Al2O3-02 has specific area of 134.691 m2·g-1 and pore structure of 0.5851 cm3·g-1 and 8.6877 nm. The obtained Pd-based catalyst TWC-02 has superior properties. After calcining the catalyst at 950 oC, Pd grains homogeneously disperse in the surface of modified Al2O3-02; even ≥1050 oC, the dispersity of Pd is still good. Alumina has the effect of structure promoter on Pd-based catalyst. The superiority of the structure character of Al2O3-02 is also proved by a light-off active test.