Since past time till now, one of the main concerns of maintaining security and survival of governments and nations has been to try to improve capabilioty level of controlling, preventing and combating the phenomenon of counter-security, especially espionage. Computer espionage which is per se considered as a new and massive figure of espionage, regarding computer nature of most major resources of information and critical infrastructure of countries, is one of the most important concerns of countries at this time which should be considered and noticed a lot more than yesterday. Although in line with combating this kind of crime, legislators have shown reactions at various stages and have incriminated the examples of cyber criminal phenomena, we will witness increase in the emeregence, spread and cheap access to information technologies and statistics of computer crimes and complexities of the methods of committing such crimes.Lack of attention to this important issue in the near future, it will inflict irreparable damage on the society’s activities and it will threaten the State social security, as well. Since police, as judicial force is in charge of detecting crimes, in addition to judges and other judicial officials’ training, police training should also be included in their lesson plans. Regarding the importance of this issue, the present research attempts to investigate computer espionage and its preventive solutions using descriptive-analytical method.