A suspended dual- microstrip meander-line （SDMML） slow wave structure （SWS） was proposed. It consists of a metal enclosure as well as a suspended dielectric substrate， on the upper and lower surfaces of which are two metal meander-lines. As there are two electron beam tunnels locating above and below the dielectric substrate， and the electromagnetic wave has symmetrical distribution， it is possible to use one electron beam in each tunnel to drive the electromagnetic wave for a higher output power. The high frequency characteristics and the beam-wave interaction results of the SDMML SWS have been investigated by using simulation software. The hot performances of this SWS show that for two identical sheet beams with a voltage of 2050 V and a current of 0.2 A， the SDMML SWS has a maximum gain of 26 dB at 36 GHz and 3-dB bandwidth of saturation power of 8 GHz. To verify the simulation result， a SDMML SWS is fabricated by using new fabrication methods including the magnetron sputtering electroplate and laser ablation. The measured reflection loss of the SDMML SWS is better than -10 dB. The transmission loss of the fabricated slow wave structure is analyzed and verified through simulation and experimental results.