The main production and metallogenetic area of chromite in China is Tibet. The chromite was controlled by ultrabasic rocks. Using the data of Oxide percentage in ultrabasic rock of Tibet, the authors classify the rocks by theory of fuzzy pattern recognition. By randomly take out tested rock method, the author find Hamming closing degree is the highest measurement in five methods. Then the author has predicted the unknown ultrabasic rock to find the 25th rock contained chromite. The result has high reliability. This method also takes the very important academic function as to fine chromite in Tibet.