Mechanical engineering is an engineering discipline that uses the laws of physics and chemistry to analyze, design, manufacture, and repair mechanical systems. Mechanical engineering is an applied discipline that studies and solves all theoretical and practical problems in the development, design, manufacture, installation, application and maintenance of various machinery based on the theory of natural science and technical science, combined with the technical experience in production practice. Mechanical engineering is a first-level discipline of engineering graduate education and a field of engineering graduate education.

The development of engineering technology not only improves human material civilization and living standard, but also destroys the natural environment. Since the middle of the 20th century, the serious problems exposed have two aspects: the massive consumption of resources (the most serious of which is energy) and the serious pollution of the environment. In terms of energy, the improvement of nuclear fission power plants, the development of solar energy, geothermal energy, tidal energy, sea water temperature difference energy, etc., can reduce the dependence on non-renewable fossil energy. In the long run, fusion is a promising and almost limitless source of future energy. Based on the future achievements of nuclear physics, mechanical engineering, together with other engineering techniques, may solve the world's energy problems once and for all by completing the development and popularization of nuclear fusion power devices in the 21st century. The use of this new energy can also reduce carbon dioxide emissions to the atmosphere.
The deposits of metal in the earth's crust and seawater are extremely rich. As long as the process of mining and beneficiation is improved and the performance of mining and beneficiation machinery is improved to reduce the ore grade that can be economically utilized, and the metal waste is fully recovered, there is no shortage of metal material resources under the condition of sufficient energy supply. After coal, oil, natural gas, etc. are no longer used as fuel in large quantities and are mainly used as raw materials for synthetic materials, the supply of non-metallic materials can also be guaranteed in the long run.
Chemical engineering, metallurgical engineering and other production processes produced by waste gas, waste water and other environmental pollution sources, by improving the process, increase purification machinery and facilities and improve its purification efficiency, in technology can be eliminated.