Congenital Heart Disease (CHD) is the most common congenital malformation in children and the leading cause of death from birth defects in infancy. Preoperative anxiety is prevalent in children with CHD, but current preoperative care mainly focuses on physical preparation, with insufficient attention to psychological stress, and conventional intervention measures have limitations. As a non-pharmacological method, therapeutic play has been proven effective in relieving children's anxiety, but randomized controlled trials (RCTs) of therapeutic play for preoperative anxiety in children with CHD are still lacking in China. This study adopts a randomized controlled design, in which children with CHD before surgery are randomly divided into the experimental group and the control group. The experimental group receives therapeutic play (including parents' participation, with intervention content designed according to children's cognitive characteristics), while the control group receives routine preoperative nursing. The effect of therapeutic play on relieving preoperative anxiety in children with CHD will be evaluated multi-dimensionally through anxiety scale scores, vital signs, and salivary cortisol levels, providing scientific evidence for clinical intervention of preoperative anxiety in children with CHD.