Disclosed is a sodium fast ion conductor. The sodium fast ion conductor comprises the chemical ingredients of Na, Sb and S at the molar ratio of (6.99-7.01) to 3 to (10.99-11.01) sequentially; the preparation method for the sodium fast ion conductor mainly comprises the steps of putting the raw materials into a crucible; putting the crucible into a quartz tube with one sealed end, vacuumizing to 0.1Pa, sintering the quartz tube, and putting into a muffle furnace, heating at the speed of 0.3 DEG C/min to 550-900 DEG C, performing temperature insulation for 8-20h, and cooling to room temperature; taking blocks out of the quartz tube, manually grinding the blocks into powder by a mortar in a glove box, or grinding the blocks by a ball mill into powder to prepare the Na<7>Sb<3>S<11> sodium fast ion conductor. The preparation method is simple in preparation process and high in repeatability; the prepared Na<7>Sb<3>S<11> sodium fast ion conductor has extremely high ionic conductivity; and the conductivity of the sodium fast ion conductor at a room temperature can be greater than 4.56*10<-3>S/cm.