As an important cooling source in the urban built environment, the park plays an important role in improving urban heat islands (UHI). In order to reveal the influence of the external environment on the diffusion of the cold-island effect, three parks in the main urban area of Chongqing City were taken as examples. ENVI was used to retrieve the surrounding land surface temperature, and the effects of external environment elements on the diffusion of the cold island effect were analyzed. The results showed as follows: (1) The cold-island intensity of Chongqing Flower Garden (2.174℃) > Shaping Park (1.442℃) > Central Park of University Town (0.631℃). (2) The architecture form and the function layout of the park surrounding is a significant role to the proliferation of cold island effect. The effect is obvious that “the wind wall” of the building hinders the diffusion of the park’s cold-island effect, and the large-scale impervious surface is spread in the direction of the important factors restricting the cold island.