This paper examined the discounting for initial public offering of convertible bonds. We got the samples in Taiwan since 1990 to 2002 and surveyed there was the existing of excess return or not. In addition, we also try to find some variables that are relative to the excess return. After testing and verifying the samples, we had some conclusion：
1.There is excess return for the initial public offering of convertible bonds. It means when companies issued the convertible bonds, they discounted the issuing price purposely by some conditions such like coupon rate or conversion price.
2.When we used multi-factors regression to verify which factors are relative to initial return, the factors “the credit ranking of issuing company” and “trade market” had powerful influence to the initial return.
3.When we used t-test to verify initial return, we found that if separating the samples with some factors like “company ages”、“trade market”、“amount of assets”、“issuing year”, the initial return had much difference between them.