Objective To investigate the association of iron deficiency with the motor ability and prognosis of patients with chronic heart failure. Methods A prospective analysis was performed for the clinical data of 286 patients with chronic heart failure who were hospitalized in our hospital from January 2019 to June 2020, and according to the presence or absence of iron deficiency, they were divided into iron deficiency group and non-iron deficiency group. The two groups were compared in terms of cardiac function, motor ability, and prognosis. Results Compared with the non-iron deficiency group, the iron deficiency group had a significant increase in N-terminal pro-brain natriuretic peptide, a significant reduction in mitral ratio of peak early to late diastolic filling velocity, and a significant increase in left ventricular end-diastolic diameter; as for cardiac function, the iron deficiency group had a significantly lower proportion of patients with NYHA grade II cardiac function and a significantly higher proportion of patients with NYHA grade IV cardiac function; as for the type of heart failure, the iron deficiency group had a significantly lower proportion of patients with heart failure with preserved ejection fraction and a significantly higher proportion of patients with heart failure with reduced ejection fraction; as for motor ability, the iron deficiency group had a significantly shorter distance in six-minute walk test and significantly shorter VO_2max and VO_2max/kg (P <0.05). Compared with the non-iron deficiency group, the iron deficiency group had a significantly higher number of patients readmitted due to heart failure within 1 year (P <0.05). Conclusion Iron deficiency may lead to the deterioration of cardiac function, a reduction in motor ability, and a poor prognosis in patients with chronic heart failure, and the level of ferritin should be monitored for such patients.