Based on integral and area, we construct a new distance for Pythagorean fuzzy set. Compared with Euclidean distance which may fail in some cases, the new distance has its advantages that can be seen by a numerical example. In addition, basic properties of the new distance are discussed. Moreover, we propose a modified TOPSIS approach based on this newly proposed distance measure. Finally, a practical example is presented to testify the efficiency and application of this new approach.