your website is very good
No offense, but that ain't a review :p
Let's begin, shall we?
First things first, I'm in Germany on a 12mb/s connection and that site took a bloddy eternity to load. Server tracing gives me Vietnam, so if you are going to have potential customers outside of Vietnam get an American or European Web space. Otherwise it’s absolutely unacceptable on my end.
You "namtrung" Logo on top is fading to white and back to the image. This is very bad on my eyes and distracts from reading the actual site. Just leave it there, no effects needed.
On the side there’s the slideshow of products being displayed. Why does it have to be a slide show? It so off putting. 3 images constantly moving about + the 3rd one even changing directions - again - make it simpler.
Pls check this image: http://www.namtrung.com.vn/cache/images/158x118-1/uploads/products/dong_co_dien_siemens_1le1_1370141495.jpg
Your watermark is cut off. Also, general optimization is needed. An almost 158 square should not eat up 20kb. If you multiply it by the 3 slideshows and all images in one slideshow, you get a pretty big amount of unnecessary data being stuffed through that poor Vietnamese copper.
Your Google + link 404-ed. Delete or replace it.
Don't wanna critizies your workflow, but judging by some image URLs your directory are as chaotic as it gets.
I cant read Vietnamese, but your "Số lượt truy cập" is bulls**t supreme. Its not a real measurement, crawlers and bots will count into it past 1000+ instances. Nobody is going to take you serious just because your site visit counter says 300000
In conclusion, it ain't bad, but could use some general improvment. I will give you the usual, it looks like any other site and a visitor will quickly forget that it even exists. Its simply too Internet 1.0
And pls, not RED FLASHY HOTLINE NUMBER DISPLAYS. Just don't.
Now for the technical stuff:
NO images have dimensions specified.
Just to put the slowness in perspective: the nibbler website test service cancled bcause of the grand load times.
You fail html and css validation in more than just one point.
And although analyze websites rarely give a rating, that should be seriously, you get an E from http://gtmetrix.com, which is actually pretty hard to achive. (Yes, its bad)
Google "analyze website" and never post again, until you worked off the major points on some test results, that you can improve.
Good luck with your endevours, and pls no flashy-red phone numbers.