Abstract: This article first introduces the concept of mental health. Mental health problem is a crucial part of the current public health crisis in cities, and it is often underestimated by the governments and the public. Studies reported the quality of urban environments has significant and enduring impacts on urban dwellers’ mental health. Further, the article points out that contact with nature has multiple positive impacts on protecting and promoting urban dwellers’ mental health. Then, the article makes a discussion on six critical issues and provides relevant research and design recommendations. Those issues include: natural landscape in working places, natural landscape in educational places, spatial oppressiveness and sky landscape, active design of soundscape, experience of sublime natural landscape, restorative effect of natural landscape on major post-traumatic stress disorders.