I will start taking bupropion to help stop smoking,i'm a heavy drinker and smoker will reducing and or stop drinking cause a seizure?

Very possibly: Bupropion not good choice if you continue to drink heavily. You can definitely get into trouble with increased risk of seizures, hallucinations, mood and behavior change, anxiety and panic attacks. Chantix similar. For the heavy drinker, nicotine replacement therapy (patch, gum, etc) is better choice. OR, if able, drink 1 drink/day or less on bupropion. Work with Doc on comprehensive quitting plan

It might: Did the prescribing doctor ask you about your alcohol intake, and did you answer honestly? If you have withdrawal symptoms, like morning tremor (the shakes), or anxiety, sweating, insomnia or other signs of withdrawal, you should not take bupropion while doing this. Talk to the prescriber or to a mental health professional about this before doing anything. You can use nicotine patches/gum instead

Possibly: Immediate release bupropion can mildly increase seizure risk, and if you are a heavy drinker if you stop cold turkey you can get withdrawal seizures or DTs. You may want to seek out a detox or rehab facility to help get into recovery.

Alcohol withdrawal: Stopping heavy alcohol use can be a risk for seizures as is bupropion in individuals at risk for seizures. I would suggest detoxing from alcohol first then addressing the smoking. There are other risks to stopping alcohol such as permanent memory loss (weinicke korsokoff syndrome) which can be prevented with thiamine. Be honest with your MD about the amount of alcohol used to make tx plan.