In Enterprise information technologies life cycle in organization, Different factors such as reengineering of processes, shift in regulations, performance improvement could cause periods of change in these Information technologies. The purpose of this study is investigation of the role of users’,knowledge of these change periods based on their perception of task difficulty. For reaching to this purpose, data of 153 staff of one public bank and it’, s four subsidiaries in Tehran based on random sampling by means of questionnaire, is collected. This study is an applied research which correlate between variables and use structural equation modeling for evaluation of cause and effects. Results by aid of SmartPLS3 software, showed that “, command based”, , “, tool procedural”,and “, business procedural”,affect users’,evaluation of task difficulties. It is also concluded that users’,with more technology experience evaluate tasks less difficult.