An occupant classifying system and method includes a weight sensing unit provided in a seat, a central processing unit classifying the occupant into any one of various classes pre-set using the information acquired by the weight sensing unit, and regulators applying power to the weight sensing unit and central processing unit and initializing the central processing unit whenever the central processing unit is applied with power. The occupant classifying system and method provides a high accuracy and reliability, since the system and method are initialized when the vehicle's ignition is started and classify the occupant by information acquired through the weight sensing unit.