Abstract: This paper investigates the implications of the coupling strengths on chaotic attractors and the predictability by varying the parameters controlling the coupling strengths of the fast and slow dynamics in a coupled Lorenz system. The results show that as the strengths of the coupling increase, low-frequency variations similar to those of the slow dynamics can be found in the fast dynamics; moreover, its attractor becomes larger. In addition, the high-frequency variability of the slow dynamics increases, leading to the enhancement of its variability and denser attractor orbits. Herein, the effects of the coupling strengths on predictability of the coupled Lorenz model are quantified using the nonlinear local Lyapunov exponent method. The results demonstrate that after coupling, the natural logarithm curves of the error growth of the coupled dynamics comprise two distinct growth rates, where the first and second periods depict fast and slow error growth processes, respectively. Furthermore, the predictability of sub-dynamics responds differently to variations in the coupling strengths. Increasing coupling strengths in the fast dynamics reduces the predictability limit for both fast and slow dynamics. However, strengthening the coupling to the slow dynamics solely heightens the fast dynamics’ predictability limit without significantly altering the predictability of the slow dynamics.