The invention provides a downhole screw motor two-way vibration cementing tool and method. The downhole screw motor two-way vibration cementing tool comprises an upper connector, an annular baffle, a motor assembly, an axial throttle valve assembly and a lower connector, wherein the annular baffle is connected to the position below the upper joint; the motor assembly is connected to the position below the baffle; the axial throttle valve assembly is connected to the position below the motor assembly; the lower connector is connected to the position below the axial throttle valve assembly. The invention further provides a downhole vibration cementing method, and the above-mentioned downhole screw motor two-way vibration cementing tool is adopted. According to the downhole screw motor two-way vibration cementing tool and method, two-way vibration can be generated in the downhole cementing process, the vibration level and vibration frequency are changed by regulating structure parameters, cement slurry under different work conditions can generate most efficient vibration, and thus cementing quality is effectively improved.