Objective To explore the hemodynamic assessment after radical surgery in children with tetralogy of Fallot (TOF) by both echocardiography and Mostcare monitor. Methods Clinical data of 63 children with TOF who underwent radical surgery in our hospital from February 2016 to June 2018 were retrospectively analyzed, including 34 males and 29 females, aged 6-24 (9.82±5.77) months. There were 19 patients undergoing transannular patch reconstruction of the right ventricular outflow tract (a transannular patch group) while 44 patients retained the pulmonary valve annulus (a non-transannular patch group) . The echocardiography and Mostcare monitor parameters were recorded and brain natriuretic peptide was tested at the time points of 0, 8, 12, 24 and 48 hours after operation (T 0, T 1, T 2, T 4) to analyze their correlations and the change trend at different time points after radical surgery. Results The left ventricular ejection fraction at T 1 (43.49%±3.82%) was lower than that at T 0 (48.29%±4.55%), T 2 (45.83%±3.69%), T 3 (53.76%±4.43%) and T 4 (60.54%±3.23%, P<0.05). The cardiac index at T 1 (1.85±0.35 L·min−1·m−2) was lower than that at T 0 (2.11±0.38 L·min−1·m−2), T 2 (2.07±0.36 L·min−1·m−2), T 3 (2.42±0.37 L·min−1·m−2) and T 4 (2.82±0.42 L·min−1·m−2, P<0.05). The cardiac circulation efficiency at T1 (0.19±0.05) was lower than that at T 0 (0.22±0.06), T 2 (0.22±0.05), T 3 (0.28±0.06) and T 4 (0.34±0.06, P<0.05). The right ventricular two-chambers view fraction area change at T 1 (23.17%±3.11%) was lower than that at T 0 (25.81%±3.74%), T 2 (25.38%±3.43%), T 3 (30.60%±4.50%) and T 4 (36.94%±5.85%, P<0.05). The pulse pressure variability was the highest at T 0 (18.76%±3.58%), followed by T 1 (14.81%±3.32%), T 2 (12.44%±2.94%), T 3 (10.39%±2.96%) and T 4 (9.18%±1.92%, P<0.05). The blood brain natriuretic peptide was higher at T 1 (846.67±362.95 pg/ml) than that at T 0 (42.60±18.06 pg/ml), T 2 (730.95±351.09 pg/ml), T 3 (510.98±290.39 pg/ml) and T 4 (364.41±243.56 pg/ml, P<0.05). There was no significant difference in left ventricular ejection fraction, cardiac circulation efficiency and heart index between the two groups (P>0.05). The right ventricular two-chambers view fraction area change of the transannular patch group was significantly lower than that of the non-transannular patch group at each time point (P<0.05). The blood brain natriuretic peptide and pulse pressure variability of the transannular patch group were significantly higher than those of the non-transannular patch group (P<0.05). Left ventricular ejection fraction was positively correlated with cardiac index (r=0.637, P=0.001) and cardiac circulation efficiency (r=0.462, P=0.001) while was significantly negatively correlated with blood brain natriuretic peptide (r=–0.419, P=0.001). Conclusion Both methods can accurately reflect the state of cardiac function. Mostcare monitor has a good consistency with echocardiography. Using transannular patch to recontribute right ventricular outflow tract in operation has more influence on right ventricular systolic function. The Mostcare monitor can guide the hemodynamic management after surgery in real time, continuously and accurately.