A method for evaluating the launch safety of ignition cartridge of a mortar bomb was studied. The cause of tail tube burst was analyzed. A method forecasting the probability of tail tube burst was established. On the basis of test results of maximum tail tube pressure, it was deduced that the distribution of maximal tail tube pressure at low temperature was consistent with normal distribution, and the probability of tail tube burst was calculated. The result shows that the probability of tail tube burst is very big, and this problem can be overcome by improvement. The forecasting method can be used to analyze the launch safety of ignition cartridge of mortar bomb.