Hello all, i just want to know if there a way to get better result of graphics in unity?
Well that’s almost entirely dependant upon the Assets you’re using. Also, there is a Quality Settings option in which you can deal with things such as texture quality and anti-aliasing.
For us to define better we’ll need to see where you’re currently at. 
EDIT: Wow, essay alert. I didn’t mean to get that elaborate but whatever.
Well, to get good art in Unity I need to run down the line:
Solid Assets: BY FAR the most important thing. if you want a great looking game on par with the hottest AAA releases then you need great, high poly models that use those polies intelligently and leave little to the imagination, and textures that not only look good on their own but also conform to the model details. For example, for hard surfaces you probably want differentiation or blending between changes in material. Additionally, your normal maps need to both cover large details to make your model seem more high poly than it is and small details for all the bumps, scratches and overall texture.
Consistency and color: This is also important. If most of your models look great but a few of them look bad, or if most of your models have a sharp realistic style to them but a few are abstract and stylistic, then your game will look like a hodgepodge and lower your visual quality. Take special note of consistency in color. You want the majority of your scenes to have a consistant color range that is predominately 2 - 5 colors that aren’t drastically contrasting. Lighting can help a lot with color, which I’ll go over now.
Lighting: From here on out these are things that are exclusively up to the Unity game engine. I think a lot of people underestimate the importance of good lighting in terms of color. Even AAA games fail in this regard in my opinion, as they offer a color scheme of mostly grey or desaturated browns or greens. Obviously the placement and intensity of your lights is important, but also finely adjust the color of the lights, the ambient lighting and the fog. Even subtle color adjustments can make a big difference in my opinion. Also, if you have Unity Pro, take advantage of shadows as they automatically add more depth. Also, unless your lighting is going to change dramatically (I.E dynamic time of day changes), take advantage of light maps.
Shaders: Make sure you have the right shaders for things. Don’t just add specularity to rocks or tree bark just becaus you think specularity makes anything look better. For things that do have specularity, adjust the specularity appropriately and consider an environment map if they are supposed to be really shiny. For humans, take advantage of the skin shader on the wiki (I recommend you change the wrap ramp on that though; I did and the results were much better). Most of the shaders you will need are either built in or in the wiki, but if you need a specialized shader you should learn how to make them.
Liveliness: If you don’t want your game to feel like a screenshot when you stand still, then add some liveliness. This encompasses non-gameplay animation, particles, lens flares and a lot of post effects. If your game has nothing changing if you just stand there then you probably need more liveliness.
Misc: Some other things that make a small but noticeable difference are things like color adjustment, which can make an image pop more and give it a more cinematic feel. Also, from a technical standpoint make sure your graphical settings are high and that the texture import settings for high detailed objects is appropriate.