Objective To investigate the gradient changes of bilateral cerebral hemisphere pressure after lateral hemisphere injury and observe their effects on craniotomy. Methods Twenty-four patients with cerebral contusion and subdural intracerebral hematoma were included in this study. All patients received brain parenehyma pressure (BPP) monitoring by introducing optic fibro sensor into each cerebral hemisphere via the frontal lobe. All patients underwent surgical craniotomy for evacuation of space occupying lesions such as cerebral hemisphere contusion, subdural and/or intracerebral hematoma.Preoperative and postoperative BPP data at different time points were recorded and analyzed. Results Preoperative BPP value of the injured hemispheres was significantly higher than that of the other hemisphere (P ＜ 0. 01 ). There was no significant statistical difference upon BPP value at 0, 24 and 48 hours after operation between both hemispheres ( P ＞ 0.05 ). The postoperative BPP value of bilateral hemispheres was lower than the preoperative one. Conclusions BPP monitoring sensors should be introduced into the injured hemisphere so that the valuable information can be timely showed. When the cerebral hemisphere has lesions after brain injury, such lesion becomes the source of elevated intracranial pressure and can result in bilateral hemisphere pressure gradient. Craniotomy can not only effectively lower the intracranial pressure, but also eliminate the BPP gradient, which contritbutes to reposition of the oppressed brain tissue.