The secondary cooling of AZ80 during DC casting was investigated by measuring the temperature at a given position during steady state. The experiment was carried out under different parameters including the water flow rate density ($Q^{*}$) and initial temperature ($T_i$) of the impingement points. To theorize the heat transfer of the secondary cooling zone in practical DC casting, we designed a series of experimental equipment to simulate the secondary cooling with differing $T_i$ (between 473 and 673 K) and $Q^{*}$ (between 20 and 100 L min⁻¹ m⁻¹) based on the DC casting temperature-measurement experiment above. Detailed analysis was carried out of both the experimental results combined with $Q^{*}$. The empirical formulae of Rohsenow and Weckman were modified due to the need to divide the secondary cooling zone into an impingement zone and a free-falling zone. Finally, a verification of the model’s accuracy was conducted by comparing the results of the finite volume numerical simulation and the experiment, which revealed that the model exhibited extremely high accuracy.