The Na doped barium strontium titanate based ceramics was prepared by the flash sintering method. The phase structure, micromorphology and the rapid sintering densification mechanism of barium strontium titanate based ceramics under different DC electric field intensity were studied.It was found that under different electric field intensities of 330 V/cm,440 V/cm,550 V/cm and 660 V/cm,the phase structure is pure perovskite structure,the 〖JP2〗average grain size decreased with the increase of electric field,and the initial temperature of flash sintering decreased with the 〖JP〗increase of electric field. When the electric field intensity reached 660 V/cm,the sintering temperature was 800 ℃.