In this article, the classification of tunnel boring machines (TBM), the stateoftheart of studies on tunnel boring machine technology, and the trend of study and development of tunnel boring machine technology are studied and discussed. Conclusions drawn are as follows: 1) According to the strength of the rocks and soils bored, tunnel boring machines can be divided into rock tunnel boring machines and shield machines. 2) The hot topics of studies on rock tunnel boring machines include the rockbreaking mechanism of disc cutters and the establishing of TBM performance prediction models. On the other hand, the hot topics of studies on shield machines include the stability of working face, the control of boring process and the study on ground surface settlement. 3) Studies on tunnel boring machine technology will focus on the improving of the boring mechanism, the boring mechanism and the boring process control under complex geological conditions, and the development of composite boring technology. 