Considering the impact on group decision making from that every decision maker has attitude toward risk and grey targets about attributes, a method of group grey target decision making with three parameter interval grey number based on the prospect theory is proposed. A linear operator with the features of the“rewarding good and punishing bad”about three parameter interval grey number is used to standardize the decision values. The positive or negative sign of the standardized values can reflect adequately whether the attributes’ values hit the bull’s eye or not. A prospect value function is defined by using the dividing point of positive and negative as the reference point. Then, the weight model of decision maker is proposed based on group’s consistency and the maximum entropy, and the project hits bull’s eye or not is judged according to positive or negative of comprehensive prospect values. Finally, the vendor selection case shows the feasibility and superiority of the proposed method.