Crystalline structures with Sierpiński triangles as building blocks were constructed via a templating method in an ultra-high vacuum and studied by low-temperature scanning tunneling microscopy. Cobalt atoms and 4,4''-dicyano-1,1':3',1''-terphenyl molecules were used to build the Sierpiński triangles. The Au(100)-(hex), Au(111)-22 ×, and stepped Au(111) surfaces were used as templates to guide the packing of Sierpiński triangles. One-dimensional double chains and two-dimensional small domains of Sierpiński triangles were successfully prepared using the method in experiments.