Based on the plasma modified model and photoionization optimization model, this article constructs a low temperature and subatmospheric pressure air streamer discharge model. Through the model, the characteristics of streamer discharge under high-frequency square wave voltage are studied. Streamer discharge exhibits a different discharge pattern from dc voltage in the voltage drop stage and low-level stage. In addition, duty cycle and rise (fall) time have different effects on parameters, such as electron density, positive ion density, electric field, space charge density, photoionization rate, and streamer propagation velocity. [ABSTRACT FROM AUTHOR]