Abstract This research is based on the Taiwan Stock Index. We can use the technical analysis of K-line which may reveal the signal of buying or selling in actual operation. It can help the investors to deciside the timing to buy or sell. The above method is a kind of stock index in actual testing analysis during the period from 1993 to 2002. The conclusions of our research are the following: 1. The signal of buying or selling can create good return according to the theory of K-line during the research period and it sometimes can offers higher return than the interest rate offered by the bank. It is a reliable method for most of the investors. 2. The signal of up or down can't be judged according to the theory of K-line during the period of stagnancy. We must judge the market and predict the future after the ending of stagnancy of K-line in order to obtain the best point of buying or selling.