Abstract: Introduced by dynamic characteristics, P-sets can be obtained from the improved finite general sets. P-sets are a set pair which are composed of internal P-sets XF and outer P-sets XF,or (XF，XF) is P-sets. By using P-sets, the concept of data internal search, the measure and dependence relation about F-data were given, search iterative algorithm and criterion of F-data were proposed,finally the applications of data internal search were given. P-sets is a new theory and method to study dynamic information system.

Key words: P-sets,F-data, Data internal search, Dependenccinternal search criterion, Applications