Objective：To establish an effective method for predicting intracranial pressure（ICP）by measuring optic sheath diameter （ONSD）using ultrasonography. Methods：52 patients with severe neurological conditions were continuously monitored for postoperative invasive ICP. The mean diameter of the optic nerve sheath in vertical and horizontal directions was measured by transorbital ultrasound. The diagnostic efficacy of ONSD in intracranial hypertension was analyzed by receiver operating characteristic （ROC）curve，and the sensitivity and specificity of the method were evaluated. Results：The mean binocular ONSD（5.27±0.47）mm was well correlated with invasive ICP（11.77±6.18）mmHg in all patients（r=0.79，P < 0.01）. ROC curve showed that the ONSD cutoff for detecting intracranial hypertension（ICP≥20 mmHg）was 5.625 mm，with a sensitivity of 74.3% and a specificity of 90.4% . Meanwhile，the ONSD cutoff corresponding to ICP 5，10，15 and 25 mmHg were 5.175，5.325，5.375 and 5.825 mm. Conclusions： Bedside ultrasound measurements of ONSD through orbit can determine changes of ICP，especially in the case of invasive ICP or limited imaging examinatior in patients with severe neurological conditions . The ICP can be evaluated dynamically，quickly and non- invasively，which has significant clinical application value and is worthy of promotion.