A division unit, an image analysis unit and a display apparatus using the same capable of simplifying the computation of overall average gray scale are provided. The division unit includes an adder for receiving a first to an Nth bus signals to produce an addition result, wherein the first to the Nth bus signals shift the input signal by a different number of bits and adding logic zeros to the shifted bits as compensation, where N is a positive whole number, and a multiplexer for receiving a most significant bit (MSB) of the addition result, wherein, when the MSB has a first value, the multiplexer treats P bits of the addition result as a division result, and when the MSB has a second value, the multiplexer outputs P logic 1 to serve as the division result, where P is a positive whole number.