Abstract: A program used for searching and matching of X-ray powder diffraction patterns was written and a library for this purpose was built by using FORTRAN-IV language. The program has been tested by using it to sdarch tens of patterns. Generally, all the existing phases can be searched out and the number of missearchings is not so large. In comparison with other programs, briefly, two major improvements have been made in the present program:(1) a so-called 'substance-type-discrimination' was introduced into the searching process which can reduce missearching remarkably; (2) a new method for quantitative intensity-matching was proposed, based on the least square method. It can give better results than the Frevel's method and provide more information to discriminate the canditates further.