I am looking for a new toilet. my old toilet flush tube is kind of small thus it frequently get clog.

Can someone recommend me a high flow toilet?

it must have wide flush tube.

I've got an older Kohler pressure-flush style toilet in the upstairs bathroom, and it's the best toilet I've ever owned. It's never gotten clogged once in 15 years, whereas ever other normal "float" style toilet in the house has clogged quite a few times. I've also never had to replace any of the rear tank mechanism, which I've had to do a few times on the other toilets.

The only downsides are it's loud (about as noisy as commercial toilets) and it was pretty expensive back when we put it in.

I don't believe they still make the particular model I've got, but, looking at their website, it seems like the "Pressure Lite" models are similar in function. Here's a video of it flushing that I found online:

http://www.youtube.com/watch?v=JrdkU-_ecCk

If it works just as well as my older model, than I wouldn't hesitate to replace all my toilets with them when it comes time.

thanks for the link. I will check it out.

Before going to the trouble of getting a new toilet I would make sure the old one is working correctly and doesn't have a hidden problem that is causing difficulties.

One of the first things to look for is clogged holes around the rim. The individual streams from them should be strong and steady. They should all be roughly the same volume and strength. Over time these tend to narrow and clog from lime buildup. Observe a few flushes and compare the jets. Get a small mirror and a flashlight and inspect the jets around the rim. Use a copper wire and brush to open any jets that are weak or clogged. I have also poured muriatic acid down the flush valve to de-lime the water channels but you have to be careful, know how to handle acid, use proper protective equipment (gloves and goggles minimum), and you can't get carried away with it or you risk etching the porcelain.

Look at the flush valve. A flush valve that doesn't open long enough or far enough will cause a weak flush action. Valves on pressure units are not immune to wear and renewing the internals with a rebuild kit can often solve problems.

Check the S-bend. A plastic army man or pencil, possibly the hardest of all obstructions to detect and get out without lifting the entire unit, can cause chronic and repeated clogging. I once pulled out a pencil stub out of the S-bend that had made a toilet unreliable for years. I had to lift the whole unit but once removed the toilet worked fine.

The other thing to consider is that any toilet will depend on the drain lines to be correct and open. A partially plugged drain line, a lack of a proper vent, lines that have sagged overt time, or a failed auto-vent will ruin the performance of any fixture. New and improved or not.

If your not up to such and evaluation ask around for a friendly plumber who will take a look and offer advice for a nominal charge. A good plumber can often tell what is going on in just a couple of minutes.