This work aims at covering the shortage of the complex measurement procedure of nonlinear two-line atomic fluorescence (NTLAF), and a new calibration method based on tunable diode laser absorption spectroscopy (TDLAS) is proposed. First, three calibration constants are combined into one. The new constant is calculated by an iteration of the fluorescence intensity and TDLAS real-time path integral temperature. Finally, the temperature profile is deduced. Numerical simulations for the calibration of NTLAF temperature by TDLAS are performed. The influence of temperature profiles and initial values is analyzed. The precision of the simulation results is almost equivalent to that obtained by conventional point-wise temperature calibration methods, and the uncertainty is within 5%. Different temperature profiles have little influence on this calibration method. A proper initial value will always result in the same final value.