how to create constant material without shadow and specular? only color.Thanks.

In the Material Palette, under the All Galleries > Materials > Utility, there's a shader called Constant. If you drag it into the right panel, it'll create an instance of that material. Then, you can drag that material onto an object that you want to apply it to. Hopefully that's what you were looking for.

You can alternatively use a Constant Value VOP as a material, but I can't remember if you need to do anything special for that to work everywhere.