Recently, camouflaging geographical origin of agricultural products is a major problem in Japan. Now we are developing a distributed system which identifies geographical origin of vegetables by analyzing, accumulating and comparing trace element compositions of vegetables. This system stores compositions of trace, or very small quantities of elements into database which located on farming districts, and compares them to trace element compositions of vegetables which gathered from distribution channel such as markets, food factories. Objective of this system is verifying geographical origin information by food traceability system and deter camouflaging geographical origin. However, in this system, all sites in farming districts must be searched to identify geographical origin. In this paper, we describe a method to reduce the number of targets to identify geographical origin using similarity preserve hash (SPH).