The invention provides an oscillating bar linkage hoisting mechanism of an underneath type plastic hollow molding machine, comprising a worktable arranged on an engine base, wherein the worktable is provided with a lower mould and an upper mould; an upper cross beam is arranged above the upper mould, and a lower cross beam is connected below the lower mould; a mould opening/closing oil cylinder is connected below the lower cross beam; a rotary tower is arranged at one sides of the upper and lower moulds; the rotary tower is provided with a core rod, and the core rod is matched with the upper and lower moulds; a main shaft is arranged in the rotary tower, and the main shaft is driven by a hoisting mechanism; a transposition box body is connected below the worktable; the oscillating bar linkage hoisting mechanism is characterized in that: the hoisting mechanism comprises an oscillating bar connected with the lower end of the main shaft; a first supporting point is arranged at one end of the oscillating bar, and the other end of the oscillating bar is provided with a second supporting point; the first supporting point is connected with the lower cross beam through a connecting assembly, and the second supporting point is connected with a supporting point oil cylinder in a retracted state through a second connector; the supporting point oil cylinder is provided with a third supporting point; and the third supporting point is connected with the transposition box body through an oil cylinder base.