In this paper, the authors have reviewed their investigation on the clinical detection of tumor tissues by infrared spectroscopy in recent ten years. Based on the comparison of different IR spectroscopic methods such as IR transmission spectroscopy, micro-IR spectroscopy etc, the authors found the good consistency of the results of ATR (attenuated total reglection) IR spectroscopic method with those of pathological biopsy. The authors have directly measured the IR spectra of frozen tissues stored in liquid nitrogen and freshly resected tissues, and have realized the measurement of tumor tissues in vito during the operation process using a specially designed IR spectrometer connected with a mid-IR fiberoptic with an ATR probe. The authors have investigated the malignant and normal tissues including parotid, esophagus, stomach, colon, liver, gallbladder, breast, thyroid etc. and compared with the pathological results. The accuracy of this novel IR detection method is more than 90%.