Currently on slimfast i eat 1200.calories a.day i'm 332lbs.is.this.okay?.

Depends: You may be ok but it would be best to work with a dietician. You can actually get "too little" calories and your body will go into starvation mode. In this, it purposely retains fat as a protective measure. There are other metabolic changes. When getting caloric intake down this low, it is best managed by a professional.

No: 332 lbs is not a health weight. You should consult a doctor or at least a nutritionist to design a well balanced diet. Consulting a doctor is also essential to see what physical activities you may safely engage in. Caloric restriction and increase in physical activity are both essential. You doctor can also advise on a healthy weight for your height and body build.