In order to obtain a comprehensive vibration parameters,LMS.Test.Lab test system was used for WEDM-HS DK7735 modal test. The test results show vibrations of DK7735 in 266~288 Hz,347~397 Hz , 875~943 Hz have maximum impact on processing quality, the vibration frequency of machine tool in the running process should be avoided in that range；machine tool lower arm damping ratio is about 0.3，the structure vibration resistance ability is poor, so the structure should be optimized；machine tool first and second natural frequencies are concentrated in 160 Hz and 285 Hz,starting from the 3rd order,natural frequency distribution is scattered.