The application of computer vision technology to detection of pear bruising was studied． It was proposed to separate different bruising spots in the same pear with the aid of regional labeling way. To improve measuring precision of bruising area, a mathematic model for calculating bruising area was put forward according to pear appearance and the characteristics of bruising. Results from experiments confirmed that, different bruising spot can be precisively detected with these methods motioned above, and most of measuring relative errors can be controlled within 10 %.