The goal of this clinical trial is to evaluate the efficacy，safety and tolerability of SR750 in patients with trigeminal neuralgia (TN). Patients will receive SR750 (study drug) or placebo for 6 weeks and keep a diary of daily pain. The study duration for each patient is up to 11 weeks.

This is a phase 2, randomized, double-blind study comparing SR750 with placebo in patients with trigeminal neuralgia. It consists of a screening period, a double-blind treatment period, and a post-treatment safety follow-up period. Baseline pain intensity and number of paroxysms will be taken in the run-in period of screening period and will be checked for eligibility. Around 162 eligible subjects will be recruited and randomized into three arms at 1:1:1 ratio to receive SR750 high dose twice a day (BID) , SR750 low dose BID or placebo BID for 6 weeks. Subjects, investigators, all clinical study site staffs, and the Sponsor will remain blinded to treatment assignment during the study. Subjects will be asked to record the number of paroxysms of pain, severity of daily average pain of paroxysms and severity of daily worst pain in e-diary over the last 24 hours every night before going to bed. After completion of double-blind period, subjects will continue to complete the safety follow-up.

Key Inclusion Criteria:

• Diagnosis of trigeminal neuralgia as per International Classification of Headache Disorders third version (ICHD-3) criteria
• Subjects must have experienced ≥3 paroxysms per day with a daily average pain sore of ≥4 and ≤8 on PI-NRS during the five days prior to randomization.
• Willing and able to undergo washout of prohibited medication as per protocol requirements and refrain from use of the prohibited medication throughout the study period.
• Female subjects must be non-pregnant and non-lactating.

Key Exclusion Criteria:

• Secondary trigeminal neuralgia
• Painful trigeminal neuropathies
• Other pains that cannot be clearly differentiated from the pain associated with TN or may interfere with the pain assessment
• Subjects have previously undergone microvascular decompression (MVD), sensory rhizotomy of trigeminal nerve, radiofrequency ablation (RFA), percutaneous balloon compression (PBC), permanent lesion of trigeminal semilunar ganglion, botulinum toxin type A for the treatment of TN within 6 months prior to screening. Subjects with severe complication after therapeutic procedure would also be excluded.
• Known history of human immunodeficiency virus (HIV) or active infection of hepatitis B virus (HBV), hepatitis C virus (HCV) or Treponema Pallidum