Urban green space has a cooling effect and can form a low-temperature area to reduce the ambient temperature, which is an effective way to alleviate urban heat island islands. This study selected 30 green patches in the suburban area of Shanghai as the research objects. Through surface temperature inversion, the cold island effect of the suburban greenbelt was evaluated from two aspects which are cooling amplitude and cooling distance, and the influencing factors of the cold island effect were analyzed from two aspects of spatial pattern characteristics and external environment characteristics of the suburban greenbelt. It is concluded that the location, layout, and scale of green space, the coupling of blue and green space, the intensity of urban development, and the relationship with the dominant summer wind direction are the main factors affecting the cold island effect of suburban green space. To improve the cold island effect of suburban green space in Shanghai, we should weigh the demand of cooling distance or cooling amplitude, then control the appropriate green space characteristics, strengthen the combination of blue and green space, and make the main axis of green space parallel to the dominant summer wind direction as far as possible.