To solve the fuzzy decision-making problem in which the criterion value and the criterion weight are given in the form of binary or ternary inter-zone numbers, an improved algorithm of interval number-binary connection number conversion is proposed. By using the preference value of interval number and the value range of upper and lower limits, the interval number is converted into a binary connection number. The preference value of the interval number is taken as the same degree of the connection number, and the distance from the upper and lower limit of the interval number to the preference value is taken as the difference degree of the connection number. The uncertainty of interval fuzzy information increases and the uncertainty decreases during the conversion process. On this basis, the positive and negative ideal solutions of the connection numbers are redefined by using the same degree and difference degree, and the distance formula between the connection numbers is determined. Then, an improved TOPSIS fuzzy decision algorithm based on the connection numbers is proposed. Finally, the effectiveness and rationality of the algorithm are verified by an example.