A Raman detecting system includes a bowl shaped metal nanostructure array configured to load a sample, a projecting module configured to project a beam of light to the bowl shaped metal nanostructure array, and a receiving module configured to collect the light scattered by the bowl shaped metal nanostructure array. The bowl shaped metal nanostructure array includes a substrate having a surface and a number of particle-in-bowl structures located on the surface of the substrate. Each particle-in-bowl structure includes a bowl shaped concave structure and a protruding member protruding from the bowl shaped concave structure. The protruding member is integrated with the bowl shaped concave structure.