Temperature determines life of insects more than many other environmental factors. The most popular method to predict the population development of insects is based on the initial population density of insects at certain time and the environment temperatures during a certain time period. However, the accuracy of the prediction may reduce because of the unknown effects of very complicated high-temperature patterns under field conditions on development, reproduction and survival of the insects. We summarized and reviewed the research results of physiological and biochemical effects of high-temperature on insects. Extreme high-temperature lead to the wax of the cuticle breaking down, lipid melting, and permeability to water consequently increasing dramatically. The concentrations of important ions in insect cells are changed at high-temperature, then consequently altering the charge state of the macromolecular components of the cell and influencing the function of the macromolecules. High-temperature makes cytoskeleton collapse and causes cells destroyed, the fatty acid composition of its phosphoglycerides changed and the "fluidity" of cellular membranes reduced. High-temperature results in an increase in the kinetic energy of the macromolecule, thereby decreasing the ionic, hydrogen, and van der Waals bonds and increasing hydrophobic interactions of the macromolecule. This, in turn, reduces the ability of the macromolecule to hold its shape and spatial conformation. The structures and functions of DNA and RNA are changed at high-temperature, thus the stable heredity of characters is badly affected. The kinds of proteins and quantities of each one in cell are changed. At high-temperature, the normal pattern of protein synthesis is suppressed, whereas the system for heat-shock conditions is opened. The spatial conformation and function of normal proteins are altered, and new proteins (such as heat shock protein) are produced at the same time. High-temperature inhabits the activity of acetylcholinesterase and disturbs the nerve conduction, and consequently makes insects lose the ability of escaping from detrimental conditions. In addition, the metabolism of lipids and oligosaccharide (e.g. fucose) is affected by high-temperature. We discussed the potential logic relations of various changes in physiology and biochemistry of insects at high-temperature, and suggested a hypothesis about the heat injury process to insects. The injury mechanisms of high-temperatures on insects maybe differ at varying temperature degrees. At last, we pointed out the important aspects in this area needed to be investigated in future. It includes (1) the most sensitive part of the insect′s body to high-temperature; (2) key steps to form a complete mechanism of heat injury to insects; (3) mechanism for induction of heat tolerance; and (4) reasons in biochemistry for different responses of different development stages of insects to heat stress.