Objective To observe the efficacy of pulsed Nd:YAG laser in the treatment of lacrimal sac fistula. Methods Twelve patients (12 eyes) with lacrimal sac fistula were treated with pulsed Nd:YAG lacrimal laser, and 7 of them with combined nasolacrimal duct obstruction were pre-treated with lacrimal laser exploration. All 12 patients were cured at once, and 7 cases with combined nasolacrimal duct obstruction were also cured, with no recurrence at 8 months to 3 years of follow-up. Conclusion The pulsed Nd:YAG laser is effective in treating lacrimal sac fistulas, and the fistula and fistulae close quickly, not only for congenital fistulas but also for acquired fistulas.