Abstract: Wheel/rail adhesion is one of the key basic scientific issues in railway transportation, and a good adhesion state of the wheel/rail contact interface is the fundamental guarantee for the safety and high-quality operation of trains. The wheel/rail contact system is an open system, which is affected by various external natural environmental factors, e.g. humidity, temperature, water, windblown sand and even iron oxides, and all of these environmental factors can affect the adhesion state and damage behavior of the wheel/rail contact interface. This work expounds on the recent research progress on the influence law of natural environmental factors, e.g. water, humidity, temperature and windblown sand on wheel/rail adhesion characteristics and the characteristic of iron oxides at the wheel/rail contact interface under natural environmental factors was analyzed. The influence of natural environmental factors on the formation of iron oxides and the influence law and action mechanism of iron oxides on wheel/rail contact adhesion characteristics were emphatically discussed, and the future research direction of wheel/rail adhesion was put forward. The constant change of the natural environment has a great influence on the wheel-rail contact characteristics. Among them, the variations of temperature, humidity, rainfall and snowfall can easily cause the phenomenon of ‘wet rail’, which directly affects the adhesion characteristics of wheel/rail contact interface. In addition, iron oxide and leaf pollution between wheel and rail contact interface also lead to low adhesion. The results show that water reducing the adhesion coefficient level between wheel and rail forms a unified understanding, while its action mechanism is still a matter of controversy. Therefore, the following research needs clarifying and unifying the understanding of the action mechanism of the influence of water media on the wheel-rail adhesion coefficient. Humidity and temperature affect the formation of oxides at the wheel/rail contact interface, and the combination of oxides and humidity further affects the adhesion performance of wheel-rail. Therefore, the influence of temperature and humidity on adhesion characteristics of wheel-rail is inseparably related to oxides. Although hard particles such as sand or alumina can effectively increase and improve the adhesion coefficient of the wheel-rail contact interface in a low adhesion state, the hard particles entering the wheel-rail contact interface will significantly increase the wear rate of the wheel and rail materials and aggravate surface damage for wheel and rail materials. This is because the hard particles are always embedded in the surface of softer material to produce furrowing action on the harder surface of friction. The results show that the formation and removal of iron oxides on the surface of the wheel and rail are affected by the operation of the wheel. Therefore, the oxidized rust layer is often worn off and regenerated, but the newly formed oxide film and peeling oxide act as a third body between the wheel and rail contact interface, which has a significant impact on the adhesion performance of wheel/rail. In order to ensure that the wheel-rail contact interface has a good adhesion state, further research on adhesion characteristics of wheel-rail contact interface can be carried out from the following aspects in the future. First, the oxidative corrosion law of wheel and rail materials and the influence of iron oxides on the adhesion characteristics and damage behavior of wheel and rail in the high humidity-heat and corrosive environment of southern China should be deeply explored. Second, the crushing behavior and optimal application parameters of hard enhancer particles in the process of adhesion improvement can be studied in depth. Third, research on wheel flange/gauge surface lubrication and wheel tread/top surface of rail adhesion control can be carried out in depth. In particular, the design and development of environmentally friendly lubricants and friction modifier to stably regulate the adhesion characteristics of the wheel-rail contact interface.