The space charge generated by corona discharge in HVDC transmission lines has a great influence on the surrounding electromagnetic environment. In order to evaluate the operation status of HVDC transmission lines in Shandong power grid, the ground level composite field strength, ion current density and audible noise of ±660 kV Ningdong-Shandong and ±800 kV Ximeng-Taizhou and Zhalute-Qingzhou HVDC transmission lines under different tower combinations are measured on the spot by the STT-HDSW electromagnetic environment detecting device and the Brüel &Kj?r 2240 high precise sound level meter, and the results are compared with the calculated values. The discharge characteristics of the transmission lines are analyzed. The results show that the composite field strength, ion current density and audible noise of the transmission lines meet the limits of the national standard. The fundamental way to reduce these values is to increase the height of the transmission lines from the ground, the wire diameter of the sub-conductors and the number of splits, properly. The research results can provide the basis for electromagnetic environment evaluation of HVDC transmission project in Shandong power grid.