Abstract: The Confocal Laser Scanning Microscopy(CLSM) is a new generation of optical microscopy. It prossesses the characteristics of convention optical microscopy as well as scanning electron microscopy, and has a series of special functions such as high magnification, high resolution, any section scanning with some depth and the reconstruction of three dimension image. It can be used to study the microstructure and the stereo image of matter, and take three dimension measurements. In this paper, the typical hydrocarbon source rocks(coals, oil shales, and oil source rooks) are investigated with the CLSM. The rimary results show this instrument has a wide application in oil and gas evaluation. It help not only to go deep into the understanding of many problems, but also to expose a lot of new geological information. The most merits of the instrument are in that a comprehensive evaluation of a source rock can be made directly by its whole rock polished blocks, which include the determination of the abundance, types, characteristics and origins of organic matter, the study of the hydrocarbon generation and migration, and the explaination of many other petroleum geological problems. Moreover, CLSM can also study some problems which are unsolved by common optical microscopy and scanning electron microscopy. For examples, it can investigate the occurence of dispersed organic matter in a source rock, study the porosity structure and evaluate fluid inclusion, particularly organic inclusions. It is pointed out that CLSM will be very important to promote the development of mineralogy, mineragraphy, petrology and other geological sciences, and to solve some related geological problems.