Abstract: Aiming at the limitations of the algorithm of interval grey number, an improved algorithm is introduced in this paper. Firstly, the limitations of the algorithm of interval grey number are analyzed, such as irreversibility, virtual amplification, and non-closure. Then, according to the "using minimum information principle" and the algorithm of a real number and its internal requirements, an improved algorithm of interval grey number is given, and some properties of the improved algorithm of interval grey number are discussed. Finally, some examples are given to verify the effectiveness of the new algorithm. The results show that the improved algorithm of interval grey number overcomes the limitations of the existing algorithm, and the calculation examples show that the improved algorithm is feasible and effective. The research results further enrich the grey system theory and provide a theoretical basis for studying grey algebra.