INTRODUCTION: Heart failure with preserved ejection fraction (HFpEF) affects more than half of the patients with heart failure. HFpEF and sarcopenia can interact with each other and contribute to reduced physiological function and increased mortality in elderly patients. Resistance training (RT) or resistance exercise rehabilitation (RER) may have benefits for elderly HFpEF patients with sarcopenia. Whey protein supplementation (WPS) may increase the effects of exercise on strength and muscle mass, in addition to promoting heart function and quality of life (QoL). However, studies are needed to evaluate effects of RER and WPS in patients with HFpEF with sarcopenia. METHODS AND ANALYSIS: This is a prospective, randomised, controlled clinical trial in which patients with HFpEF with sarcopenia will be randomly allocated to three groups, control, RT and RT+WP. Participants in all groups will receive basic intervention including standard medicine treatment, home-based aerobic exercise and basic nutritional intervention. The RT group will undergo resistance exercise programmes, and the RT+WP group will receive daily WPS apart from resistance exercise. The study variables will be evaluated at baseline and 12 weeks. Primary outcome measure is the change of 6 min walking distance. Secondary outcomes include parameters of muscle status, cardiac function, nutritional status, QoL and major adverse cardiovascular events. The primary efficacy analysis will follow the intention-to-treat principle. ETHICS AND DISSEMINATION: This study was approved by Ethics Committee of China-Japan Friendship Hospital for Clinical Research (No. 2022-KY-003). The results of this study will be disseminated via peer-reviewed publications and presentations at conferences. TRIAL REGISTRATION NUMBER: ChiCTR2200061069.