Abstract: The distribution of foci and lymph nodes of thirty patients injected with 99Tcm-MIBI are detected to differentiate which is benign or malignant by γ-detecting Probe (GDP) intraoperatively. The results of GDP detecting the malignant foci are all positive, and the benign foci are all negative. The positive rate of GDP detecting the metastatic lymph node is 100%, the specificity is 93. 6%, and the accuracy is 94. 4% under the study condition. The results of the study indicates that the method of intraoperative detecting the focus and lymph node by GDP and judging which is benign or malignant with "Tcm-MIBI injection is of high sensitivity,good accuracy and specificity.