Adverse weather is one of the many risks associated with general aviation. Weather-related accidents still account for a significant mortality rate of general aviation accidents. This usually occurs while pilots flying the visual flight rules (VFR) into instrument meteorological conditions (IMC). VFR flight into IMC continues to be a potential safety hazard among general aviation (GA). VFR meteorological criteria allow pilots to maintain flying by reference to external visual cues of horizontal visibility and cloud height limits. While flying in IMC makes it more dangerous and challenging to pilots. There are no enough visual meteorological cues like reference to the horizon. Pilots must control their aircrafts by relying upon the aircraft’s instruments. When pilots undesignedly encounter clouds or haze and cannot see the horizon, the dangerous situation can lead to pilots losing control of the aircraft. Meteorological factors have important effects on aeronautical activities. For American helicopter accidents, though only 200 accidents have occurred under IMC in 30 years, they have more damage and higher fatal rates. As a result, IMC is a vital factor threatening flight safety. By National Transportation Safety Board (NTSB) database, among weather-related aviation fatal accidents in the United States between 1982 and 2013, meteorology played a leading role in 35% of major accidents, of which 60% were accompanied by IMC. Nearly half of helicopter accidents in IMC were linked to decision making errors. Besides, ATSB database indicates that a third of pilots chose to fly into IMC and were physically injured or died when facing with adverse weather. Flying into the IMC poses a great threat to aviation safety but only a few pilots manage to avoid doing that. The aim of this study is to systematically review the psychological causes for flying VFR into IMC. Some of the underlying causal factors in VFR flight into IMC relate to pilot characteristics. In this study, we analysis six mental factors. (a)Knowledge and experience. Pilots with more experience can be better at diagnosing and identifying emergencies than those with less experience. And experienced pilots are more confident in the accuracy of their judgments. But there are also studies showing that pilots with more experience and longer flight time perceive less risk than novice pilots. (b)Situation assessment. Situation assessment theory suggests that pilots continue to fly into adverse weather conditions when they misjudge the situation they face. Specifically, compared with novice, experienced pilots can be better able to correctly judge adverse weather and thus decide to deviate quickly. (c)Risk management. Risk management is an essential skill for pilots. It concludes risk perception and risk tolerance. In general aviation, risk perception is related to flight decisions during visual flight. When encountering bad weather, pilots choosing to continue flying perceive lower risk than those choosing to deviate the plan. Risk tolerance relates to the amount of risk an individual is willing to accept in a given situation. Studies have found that risk tolerance is associated with risky behavior, and pilots who are willing to take risks have higher risk tolerance than pilots who are unwilling to take risks. (d)Theories on decision making. Sunk cost effect, prospect theory and escalation of commitment all affect decision making. (e) Cognitive biases. The use of different three cognitive heuristics can lead to cognitive biases and influence the process of flying. (f)Social pressure. Social pressure can also affect the process of pilots flying into IMC. Through the analysis of the NTSB database, we know that IMC has damaging effects on flight safety. And combining with relevant literature, we conduct a psychological attribution to the problem. Pointing at those factors, we propose some solutions such as promoting relevant machine systems and enhancing pilot mastery of aviation weather. It is important to pay attention to the harm of meteorological factors and ensure the aviation safety.