The measurement of leaf scorch area is of important significance for plant growth and plant diseases and insect pests forecasting.Taking the leaf of tea for example,leaf scorch area was measured with computer image processing technique for automatic measurement in the paper.Firstly,the image of tea leaves were got using the digital camera.Then it was input to a computer for leaf image preprocessing,RGB color statistics,threshold,color component filtering,pixel statistics and designated area ratio calculation.Finally,the tea scorch area ratio was given.The results of experiment showed that the measurement of leaf scorch area ratio was effective.