BACKGROUND: Hypophasis is one of the most frequently observed sequelae of patients with Bell's palsy, who have not recovered completely, creating a clinical difficulty for physicians. Acupuncture therapy has been widely used to treat Bell's palsy as a reasonable resolution for management of symptoms such as hypophasis. The number of acupuncture points (acu-points) is frequently selected in the approach of acupuncture therapy; however, whether these had high efficiency has not been proved. According to the literature review, Bi'nao was useful for treating eye and eye lipid diseases, which could be proved only by some successful cases. Thus, a randomized controlled trial was designed to evaluate the efficiency of the acu-point Bi'nao. METHODS/DESIGN: Participants with hypophasis as the major symptom are selected among patients with Bell's palsy and randomly allocated into one of the three groups at a 1:1:1 allocation ratio. All participants receive conventional acupuncture therapy; however, those assigned to the real acupuncture group will be given added acupuncture therapy on the acu-point Bi'nao, while those assigned to the sham acupuncture group were given extra acupuncture therapy on the sham Bi'nao as a placebo. The efficacy of the acupuncture therapy on the acu-point Bi'nao for hypophasis will be evaluated by Eye Crack Width Measurement (ECWM) and Eyelid Strength Assessment (ESA) before and after therapy. DISCUSSION: This is the first study assessing the safety and efficiency of Bi'nao in treating the hypophasis of patients with Bell's palsy that might support the application of this acupuncture therapy. However, evaluating hypophasis is challenging, and, thus, ECWM and ESA were applied to measure the eyelid movement. TRIAL REGISTRATION: Chinese Clinical Trials Registry, ChiCTR-INR-17012955 . Registered on 12 October 2017.