well Ive got my technique down and ive got a pretty good power in my strikes. The problem is that sometimes my wrists cant take it and ends up injuring myself if i continue. So does any of you have any times to strengen my wrists rock hard.

Sorry, but if your technique is good, then the impact will travel in a linear fashion through the wrist, giving it no reason to 'give' and injure.
Its more likely that as you get into your bag work, and increase your power, you are losing technique and wrist alignment.
Reign back on the power for a bit, and work on technique even more. Even the strongest, thickest wrist can snap like a twig if it folds under from throwing a bad punch.

Agreed with Cord. Most likely your technique needs some work. Less power and more concentration on proper alignment.

mmm yeah I realised what i said after i posted but w/e I waited someone to correct me. But yeah i still would like to strenghten my wrists!

farmer's walks, deadlifts, most weight lifting will strengthen the forearms.

Also, having weak wrists isn't that bad, if you get in a fight and your wrist swells afterwards, I don't think you'll be too disappointed! Honestly I often work on the bag with handwraps or even bag gloves, because even if you compete you will be wearing covering on the hands. When training you should be considering avoiding long term injuries, rather than injuries you might get in a fight. The risk of getting dodgy wrists in my opinion definitely justifies wearing bag gloves when using the heavy bag.

oh yeah i already injured myself a few times ive had this bag since chistmas im on it everyday its in my room like 4 feet behind me. I always wear my 10 ounce gloves and if i start hitting really hard i put my wraps on.

make sure you aim to land your punch with the ring finger, this way it will land over pinky, ring and middle evenly. This is your 'power line' as explained by jack dempsey. Punching this way will avoid wrist and hand injuries.

Hmmm, when hooking to the body I was taught to hit with the first 2 knuckles (index and middle).

hi,

As was said any wrist can bend to breaking point.

Knuckle pushups ad infinitum, Makawari work and heavy bag work with more attention to proper wrist alignment than power, after a decently long while of attention to fist/wrist/forearm alignment add some power and then after another decently long time it becomes habit...only a soft moving body adds a dimension not trained for...Time, be patient and go slow, what you want doesnt come overnight.

Remember, how you practice is generally how you will preform/react.

-Karl. Peace. PS along this path I've fractured a small bone in the wrist/carpal interface commonly called the "snuffbox", do not take fractures or dislocations lightly, see a MD as some fractures can affect processes of bone where ligament attaches muscle, healed improperly loss of said muscle may result.