The effects of several lasers such as Ho:YAG, Nd:YAG frequency-doubled Nd:YAG lasers, on creating transmural channel in isolated swine heart were investigated. Light microscopy was used to assess the histologic characteristics of laser-induced thermal damage and the channels diameter. The pulse number of creating a transmural channel was recorded. The results showed that the frequency-double Nd:YAG laser, as well as Ho: YAG can effectly creat the transmural channel with less thermal damage.