Abstract：By means of thermal infrared imaging detection on the transient process of rock impact with low velocity，the experiments with variable impacting angle，moisture and lithology are carried out. It is discovered that (1) there exists a critical velocity when rocks subjected to a normal impact，and the critical velocity varies with the rock types and it is about 15 m/s for marble，(2) the radiant characteristics are closely related to the impacting factors，and as to marble subjected to a normal impact within the critical velocity，the increment of thermal infrared (TIR) radiant flux is of linear correlation with the impaction kinetic energy，and the increment of TIR temperature is of conic correlation with the impacting velocity，(3) the radiant characteristics varies with the impacting angle，the radiant intensity in normal impact is almost the weakest，and it reaches the maximum value when the angle is about 45°，and (4) wet and dry rocks show difference in radiant characteristics under impact，and the trend of difference is relevant to the velocity.
