In this paper, based on the Coherent Population Oscillation principle, a general theory of time delay in erbium-doped fibers under the action of dual-frequency (1480 and 980 nm) laser pumping at different temperatures is presented. The relationships between relative modulation attenuation, time delay, fractional delay, refractive index, group velocity and modulation frequency in dual-frequency laser-pumped erbium-doped fibers with a signal wavelength of 1550 nm are studied through numerical simulation. The fractional delay reflects the information storage capacity of the medium, where a larger fractional delay value corresponds to stronger storage capacity. As demonstrated in Sect.  “Numerical simulations and discussion”, when the temperature T =  − 40, 0, 20, 40 and 70 °C, the maximum time delay is 0.9153, 1.0081, 1.0397, 1.0713 and 1.1403 ms, respectively, an increase in temperature leads to a rise in fractional delay, indicating enhanced storage capacity. Furthermore, at a modulation frequency of 10 Hz, this study investigates the relationships between refractive index, group velocity, and modulation frequency in dual-frequency laser-pumped erbium-doped fibers across varying temperatures when the temperature T =  − 40, 0, 20, 40 and 70 °C, the maximum fractional delay is 0.010079, 0.011189, 0.011574, 0.011949 and 0.012771, respectively. Results reveal that the group velocity of slow light decreases with increasing temperature. Finally, we investigated the maximum time delay, maximum fractional delay, and group velocity of different signal wavelengths at various temperatures, using a signal light wavelength of 1535 nm as the demarcation point. When the signal light wavelength is less than 1535 nm, as the temperature rises, the maximum time delay and maximum fractional delay decrease, while the optical group velocity increases. When the signal light wavelength reaches 1535 nm, the maximum time delay and maximum fractional delay increase with rising temperature, and the optical group velocity decreases. This paper demonstrates that more suitable optical transmission speeds can be obtained by adjusting the signal wavelength and operating temperature, which may have important application values in optimizing optical communication systems.