Today, the elderly spends more time in the outdoor environment than any other age group, and this outdoor activity helps improve their health. Therefore, the environment outside the residential area is important for the use and health of the elderly. Environmental assessment tools can identify and improve the problems of older people in using outdoor environments. This study employed Senior Outdoor Survey (SOS) technique to assess the effectiveness of the outdoor environment of Beishan Park, a residential outdoor environment in Qingdao, Shandong. SOS is a valid and dependable evaluation instrument that may be used to ascertain the requirements and preferences of senior citizens in outdoor settings. The outdoor environment is divided into three parts and five assessment areas. The final average score of the entire outdoor environment of Beishan Park was excellent: 84.49, accounting for 87.9% of the total score, with an inter-trainer ICC of 0.926 and a T-test value of 0.87. According to the results of the five main domains of SOS, Beishan Park is revealed as an elderly-friendly and safe outdoor environment effectively. The results will contribute to the literature in the Senior Outdoor Survey research, construction industries, building environments, and parks designed for elderly people. Project managers and park designers can also be suggested to use the SOS tool to evaluate the outdoor facilities and maintenance priorities required for the elderly.