3d arrow looks not good?

Hi.

I can’t make a arrow like this (Red arrow):

My arrow looks dark and a little bit green.

The default unity scene setup is with a slightly yellow directional light, and a blue ambient color. You’re using a lit material which is getting lit with blue light in the shadows, hence the greenish color.

You either need to adjust your scene setup, use a shader that ignores lighting, or write a custom shader that ignores the light color.

After hours of searching and trying its not working. I didn’t found something. It should also work on mobile. But, thank you.

As @bgolus said, your arrow is lit by the skybox, which is blue. The easiest way to fix this, if you don’t know anything about shaders and don’t want a blueish ambient color is to go to:
Window->Lighting->Settings (If you’re on Unity 5.5 or lower it is just Window->Lighting) and then set the environment lighting to gradient or color and choose to color you want. If you don’t want any tints, just take grey-scale values: