Objective To alleviate separation anxiety for mothers of children with congenital heart disease, and meet their needs. Methods A total of 68 PICU children with congenital heart disease were divided into two groups chronologically. The mothers of the control group contacted with PICU medical staff using the routine method when the children hospitalized in PICU, who visited their children only in detecting time, while the mothers of the experimental group contacted the medical staff and their children additionally using an ICU mobile App. And the effect was evaluated using the Critical Care Family Needs Inventory scale (CCFNI) and the Maternal Separation Anxiety scale (MSAS).Results After the intervention, the score of CCFNI and MSAS of the mothers in the experimental group was 2.75±0.49 and 2.39±0.44, which was 2.15±0.55 and 3.77±0.46 for the mothers in the control group, and there were significant differences when compared the score for the mothers of the two groups (P<0.05,P<0.01). Conclusion Application of the ICU mobile App is conducive to alleviating separation anxiety for the mothers of PICU children with congenital heart disease, and enhancing their level of needs fulfillment.