Objective To study the effect of family sandplay therapy on preschool children with separation anxiety disorder(SAD),in order to provide basis for developing an effective intervention model. Methods Sixty children with SAD were randomly selected from Dalian Women and Children's Medical Center Group from January 1st,2019 to December 30th 2020,and were divided into control group(n=30) and treatment group(n=30). The control group was given health education on SAD,while sandplay therapy and health education on SAD were implemented in treatment group with the frequency of 1 to 2 times/week,40 minutes/time. The Spence Children's Anxiety Inventory(Chinese version) was administered before,after 7,14 and 21 interventions. The treatment reports of the therapists and the treatment feelings of family members were recorded. Results After 21 times of family sandplay intervention,the scores of generalized anxiety,social fear,obsessive-impulsive disorder,physical injury fear,separation anxiety and total anxiety of children in the treatment group were significantly lower than those of the control group(t=2.002,7.300,8.160,12.138,11.676,9.370, P<0.001). Before and after intervention,the differences in scores of generalized anxiety,social fear,obsessive-impulsive disorder,physical injury fear,separation anxiety,and total anxiety in the treatment group were significantly higher than those in the control group(t=6.758,3.953,3.478,5.471,7.027,6.012,P<0.001). After 14 and 21 interventions,the total anxiety score of the treatment group was lower than that of the control group(t=3.934,7.889,P<0.001). Conclusion Family sandplay therapy can reduce the anxiety level of preschool children with SAD after a certain course of treatment.