Abstract: Independent component analysis (ICA) is a broadly used method for blind source separation (BSS). The mature ICA model has a restriction that the number of sources must equal that of sensors used to collect data, which is hard to meet in practice. An overdetermined ICA method was proposed and successfully used in the analysis of human colonic pressure signals. Using principal component analysis (PCA), the method estimated the number of sources and reduced the dimension of observed signals so that it is the same with that of the sources; and then, FastICA was used to estimate all the sources. From 26 groups of colonic pressure recordings, colonic motility patterns were extracted, which not only proved the effectiveness of this method, but also would greatly facilitate further medical researches.