This article introduces a simple method of locating the centroid of the stick-like object. By supporting the object with two fingers at each end and slowly moving them towards each other, the position of the centroid will be revealed under the works of supporting and frictional forces. The article starts with the ideal model abstracted from a pen and presents additional analysis of the physical principle in the progress. Through semi-quantitative experiments, compared with some traditional methods to find the centroid, this article illustrates the advantages and disadvantages of the new method. The principle of this method has certain application value in teaching, popularization of science, life and production.