This invention relates to a kind programmable controller numerical control cycle voltage falling simulative generator, its character is that, it is compose of industry man-machine interface touch screen, programmable controller, step motor drive, step motor, auto-transformer, zero cross sample circuit, AC-DC voltage inverter, IGBT voltage control circuit, the industry man-machine interface touch screen connects the programmable controller, the programmable controller links with zero cross sample circuit, the step motor drive, AC-DC voltage inverter, IGBT voltage control circuit separately, the AC-DC voltage inverter links with the auto-transformer and the IGBT voltage control circuit separately, the step motor drive links with the auto-transformer by step motor. The merits of this invention is that it uses the new programmable controller (PLC) with A/D transition function, realizes the control to the cycle voltage falling simulative amount which meet the related standard request. The anti-interference of this invention is good, the reliability is high, and it is easy to update the software following the emendation of related test standard.