Considering that childhood is a period of lasting effects throughout life, examining the impact of educational environments on the personality, psyche, and behavior of young children is of increasing importance. This issue is a key point in the case of children who, due to emotional dependence on their parents, especially their mothers, suffer from separation anxiety disorder when entering social educational spaces. Among the treatment methods for the aforementioned disorder, mutual parent-child therapy is considered to be the most appropriate option in the early stages of treatment. This treatment process is best carried out in an environment with special characteristics that facilitate the treatment process. Mother-child classes are among these targeted spaces that, by utilizing the biophilic approach as a design method integrating natural elements and man-made spaces, can pave the way towards improving the quality of social life, psychological well-being, and reducing children's anxiety. In this regard, the present applied research, using a library-field method with a structured questionnaire for pre-test and post-test design and a statistical population of children aged 3 to 5 years old along with their mothers in one of the centers of mother-child classes in Karaj, Iran, seeks to investigate the role of biophilic design of the mother-child class in reducing separation anxiety in children aged 3 to 5 years old and ultimately concludes that applying this design approach in mother and child classes has a significant impact on eliminating or reducing attention, physical, aggression-related, and social and personality problems stemming from separation anxiety disorder in children aged 3 to 5 years old.