A self-switch off devices controlled capacitor（SDCC） reactive power dynamic compensation device is proposed to meet local random compensation.The circuit principle of reactive power dynamic compensation for adjusting capacitor voltage is described.The switch circuit consisting of reverse blocking device is adopted to adjust the charge and discharge voltage of compensation capacitor and achieve the dynamic control of load reactive power compensation by using capacitor.The working principle and process for adjusting reactive power dynamic compensation of capacitor voltage as well as selection of main elements parameters are analyzed and described by example.It is verified by the sample that SDCC reactive power dynamic compensation device can meet the requirement of local and random compensation.