The invention relates to an atmospheric and vacuum distillation unit atmospheric pressure tower top dry point prediction method. In the prior art, there is no atmospheric pressure tower top dry point soft measurement method. By using the method of the invention, the above problem is solved. In the atmospheric and vacuum distillation unit atmospheric pressure tower top dry point prediction method, through a registration prediction system, atmospheric pressure tower top dry point prediction is performed. A prediction system is installed on a server. The server is connected to servers of a real-time database system and an LIMS system through a cable. A client is a computer and a mobile terminal with an authority so that the above problem is well solved, and the method can be used in an atmospheric and vacuum distillation unit.