The ultrasupercritical 1 000 MW units of Dongfang Turbine Co., Ltd. which have been put into production, are found to have the partial steam leakage problem in high pressure casing split. Based upon the past experiment, this paper develops some targeted construction measures, including proper handling the clearance of casing split and radial clearance of vapor lock, adjusting the clearance of the paw rest pin, adopting reliable sealing grease and thermal tightening of bolts, and so on. These measures work fine during installation process and avoid the steam leakage successfully.