Environmental temperature exerts significant influences on neuronal firing and information encodings. Concepts on the mechanisms of the respective effects are still elusive and controversial. In our study, we examined the effect of temperature on firing patterns in a model cortical pyramidal neuron. It was found that a variety of firing patterns is obtained under different temperatures. In addition, the transition modes between these firing patterns display a clear periodic bifurcation phenomenon when the temperature varies within a certain range. Several typical bifurcation modes were found, in particular period-doubling bifurcation and period-adding bifurcation.