Information and communication technologies enable people to access to various documentations and information. Huge documents and information in the Internet or storage disks have made search time more important. Especially as the volume size and the number of documents on the Internet increase, string search times and costs increase have become big burden to search service. But, most of string searching algorithms have not consider lexical structures nor vowels’ occurrence frequency. Formal documents (articles, news, novels, etc.) have important characteristic that is ‘well-formed written’ English. And words of formal documents have ‘limit number of words and alphabets’ that are listed in a dictionary. The ‘limit number of words and alphabets’ has predictable occurrence probability in real world’s documentations. We try to use the alphabet occurrence probability as first search condition. We analyze all the words in the dictionaries (dictionary of free dictionary project, scrabblehelper–Revision 20, Winedit dictionary) and calculate each alphabet occurrence probability of repeated vowels, repeated consonants, not-repeated vowels and not-repeated consonants. In this paper, we define and propose the search rules and string searching algorithm, based on occurrence frequency and patterns of vowels and consonants. We use only the occurrence patterns and repeated positions of vowel and consonant in a text. Therefore, in the real world, proposed string searching algorithm (OFRP algorithm) is based on occurrence frequency and repetition pattern of vowels and consonants and is usefully and effectively applied to string search service and web search engine.