Compared with traditional bonding methods, wafer direct bonding at low temperature has the advantages of low bonding loss, no intermediate layer pollution and no external electric field assistance. It has important application potential in power semiconductor optoelectronic and power electronic devices, high power solid-state lasers, MEMS, optoelectronic integration and other fields. In this paper, the physical and chemical mechanisms of hydrophobic bonding, hydrophilic bonding and plasma-activated bonding are introduced emphatically based on the development of low temperature direct bonding technology. The technological processes of low temperature direct bonding and the characterization method of bond strength are described systematically, the development trend of low temperature direct bonding technology is discussed, and the improvement and innovative application of low temperature direct bonding technology are prospected.