I suffer from rapid heart rate due to graves' disease and i take propranolol, can i still donate blood?

Unlikely: I would think that the elevated levels of thyroid hormone alone would be a significant contraindication, but i'm not a blood bank expert and can't say for sure. Donating blood would not pose a serious risk to you, yourself.

Probably: Unless you have a chronic transmissible infection or bleeding disorder, there is no contraindication to blood donation simply due to the graves disease. I would discuss this with the local blood bank though just for confirmation.

Yes: You should be able to donate blood if your blood pressure is stable.

Other issues: The graves disease may not be a major issue, but any medication you take might. Check with the bod bank to find out.