Objective: Fear of progression (FoP) is a common psychosocial problem among adult cancer patients, but data on parents of children undergoing cancer treatment are scarce. This study aimed to determine the prevalence of FoP in parents of children undergoing cancer treatment and explore the associated factors. Methods: Overall, 285 parents of children undergoing cancer treatment were recruited from three general hospitals in China. FoP in the parents was assessed using the Chinese version of the Fear of Progression Questionnaire-parent version (FoP-Q-SF/PR). Other questionnaires included the Self-Compassion Scale, Pittsburgh Sleep Quality Index, Posttraumatic Stress Disorder Checklist-Civilian Version, and items on socio-demographic and medical characteristics. Pearson correlation and multiple linear regression analysis were used to identify factors associated with FoP. Results: A total of 75.1% of the participants showed dysfunctional levels of FoP. The mean FoP-Q-SF/PR score was 39.98 (standard deviation = 9.18). Parental FoP was significantly associated with a shorter time since diagnosis, lower levels of selfcompassion, poor sleep quality, and severe posttraumatic stress symptoms (Adjusted R Squared = 0.369, F = 12.838, p < 0.01). Conclusions: FoP is a frequently reported problem among parents of children undergoing cancer treatment. In this cohort, parents of children with a shorter time since cancer diagnosis were at higher risk of suffering from FoP. Interventions to enhance self-compassion, improve sleep quality, and mitigate posttraumatic stress symptoms may help with the psychological adjustment and well-being of parents whose children are undergoing cancer treatment.