Sparganosis is an infection by the parasitic tapeworm larvae of Spirometra species. Ocular sparganosis is a rare disease that is easily misdiagnosed. We reported a rare case of ocular sparganosis mimicking orbital idiopathic inflammatory syndrome at initial presentation. A 34-year-old female presented with rapid progressive swelling of her left eyelid and mild proptosis for the duration of one month. The other ocular examinations were normal and the thyroid function was normal. Magnetic resonance imaging revealed a fusiform enlargement and mild heterogenous enhancement of the superior oblique muscle of the left orbit. First she received prednisolone therapy and the proptosis partially improved. Six months later, a white, flat and wrinkled string like worm wriggled out from the caruncular conjunctiva of the left eye. The pathology results confirmed that the worm was a Spirometra species larva. After removal of the larva and treatment with praziquantel, the proptosis was resolved without recurrence. Ocular sparganosis is a rare disease and only a few case reports have been reported. The drug therapy has not been effective and the surgical removal is the principal therapy. Despite its rarity, ocular sparganosis should be considered as a possible cause of orbital inflammation in patients.