Abstract: Plasma synthetic jet (some called "spark jet" or "pulsed-plasma jet") is a new type of plasma aerodynamic actuation. It is a synthetic jet that is generated by striking an electrical discharge in a small cavity and the gas in the cavity spurts out through a small orifice in a high speed after pressurization owing to the heating caused by electrical discharge. To study the performance characteristics of two-electrode plasma synthetic jet and the influence of different actuator orifice shapes, a phenomenological simulation of two-electrode plasma synthetic jet built by a single energy deposition was accomplished by equating the physical effects of the spark discharge with gas Joule heating and adding source term in energy equation. The kinetic energy and heat injection into outer flow field of plasma synthetic jet were used as characterizations of "impact effect" and "thermal effect". The results show that the kinetic energy and heat injection of plasma synthetic jet are mostly concentrating in primary jet during the self-sustained oscillation process established by a single discharge, and "thermal effect" of jet works longer than "impact effect". Overall energy efficiency of two-electrode plasma synthetic jet actuator is about 2.3% at 1atm. The influence of different actuator orifice shapes was studied and it shows that shrinking orifice can effectively improve the jet velocity, but will reduce jet momentum and saturation frequency simultaniously.