The heat transfer deterioration of an ambient air vaporizer in the process of its operation may bright about disastrous consequences, so this difficulty shall be concerned and solved in the process of LNG regasification. After reviewing and summarizing the research achievements and status of the heat transfer problems in ambient air vaporizers, this paper mainly illustrated the characteristics of the flow boiling heat transfer inside the tube and the development of its heat transfer coefficient relation. Then, the frosting process outside the tube and its effect on the heat exchange performance of an ambient air vaporizer were analyzed. Finally, the current problems in the research of vaporizers were analyzed and summarized, and the research direction for further solution of heat transfer deterioration was prospected. And the following research results are obtained. First, the flow boiling of the organic mixture of multi-component alkane dominated by methane inside the tube is the research difficulty in the future. Second, the experiments on the flow boiling inside the LNG vertical tube shall be researched further. And besides heat flow density, dryness fraction and mass flow rate, the effects of inlet pressure, tube diameter, tube length and inner wall roughness shall be investigated. Third, frosting outside the tube is the main reason for a vaporizer's heat transfer deterioration. Fourth, improving the low-temperature surface anti-frosting technology is the key point to solve heat transfer deterioration, and it is of universal significance in theoretically guiding the design, manufacturing and operation of ambient air vaporizers. Fifth, compared with the frost restraining and removing agent with hydrophilic material, the one with hydrophobic material is more suitable for an ambient air vaporizer. In conclusion, the research results are conducive to solving the heat transfer deterioration of ambient air vaporizers.