Fault tree analysis (FTA) is an important analysis method in safety system engineering, however, the method only can be used to analyse a specific accident but cannot analyse the whole generation and development process behind it. After the occurrence of top event, the consequence of the original accident probably expands to result in the expansion of the accident owing to the appearance of some specific factors. Aiming at this, the concept of an evolving fault tree is proposed to rationalise the original fault tree. By undertaking consequence reasoning, the evolving fault tree is constructed based on the original fault tree. Afterwards, through qualitative and quantitative computation of the evolving fault tree, the accident cause and logical relationship between accident factors are further revealed to identify control points for accidents. This helps when reducing, and even precluding, the occurrence of accidents. (C) 2018 Published by Elsevier B.V. on behalf of Institution of Chemical Engineers.