With the continuous improvement of China’s urbanization, the upgrading of the living environment and consumption demand by residents has stimulated the development of green urban spaces. To truly benefit the green ecology of residents and promote the ecologically sustainable development of the city, the investigation of this study found that only focusing on formal green space is not effective enough, and informal green space with high contact frequency and diversified types of green space are often ignored. This study sets up two scenarios of whether or not the informal green space system is considered in Qingdao city, and obtains accessibility under two scenarios by constructing a transportation network through ArcGIS. The results show that the accessibility distribution of urban green space is more uniform when informal green space is considered when compared with no consideration for informal green space, which reveals and emphasizes the contribution of informal green space in improving the accessibility of urban green space.