Composite films with ferroelectric nanowires serving as fillers, exhibit high adiabatic temperature change to meet the requirement for solid-state refrigeration, and their parallel-distributed filled nanowires are considered to be the key factor because their orientation is different from the orientation of the conventional perpendicularly distributed filled nanowires. However, the underlying mechanism of the electrocaloric effect of parallel-distributed nanowires has not been well understood. In this paper, a parallel-distributed PbTiO ₃nanowire model is established to investigate the effects of surface stress and solid solution modification on their electrocaloric effects through phase field simulations. The results show that an adiabatic temperature change of 5 K can be obtained near 200 ℃ with 1.5% compressive stress under an electric field of 260 kV/cm. In order to further reduce its operating temperature, the electrocaloric effects of PST nanowires with different Sr contents are calculated, and it is found that the lower the doping amount of Sr, the higher the phase transition temperature of PST nanowires is. When the doping amount of Sr is 0.45, the phase transition temperature of the nanowires can be reduced to near 100 ℃, and an adiabatic temperature change of more than 8 K can be obtained under an electric field of 600 kV/cm. Even in the low-temperature interval from 50 to 100 ℃ the nanowires exhibit an adiabatic temperature change close to 8 K. The nanowires are also characterized by an adiabatic temperature change in a low-temperature interval from 50 to 100 ℃. At the same time, by combining the evolution of the simulated three-dimensional domain structure, it is revealed that the underlying mechanism of the change of the electrocaloric effect under surface stress and solid solution modification is due to different types of domain transformations. Finally, the combinations of components and surface stresses corresponding to the maximum value of the electrocaloric effect at different operating temperatures are discussed and analyzed. The present study provides useful theoretical guidance for developing solid-state refrigeration based on parallel-distributed ferroelectric nanowires.