The purpose of this study is to exam the different of magnet effect after relaxing the price limits. We get relevant data from Taiwan Stock Exchange and Taiwan Economic Journal. To detect the difference of magnet effect before and after system reform, we used the stock of Taiwan Mid-Cap 100 Index as a sample and referred to the model of Hsieh, Kim and Yang (2009). The results show that when the stock is going up, the position of the magnet effect started before and after system reform is within four ticks of the upper price limits, there is no delay or early occurrence of magnet effect. When the stock is going down, the magnet effect before the system reform is within three ticks of the lower price limits. However the magnet effect after the system reform is not obvious. The outcome of down model is inconsistent with the up model.