A micro-fluidic oscillator is used to control a linear actuator in a dynamic microsystem. The pressure difference at its two output ports causes the linear actuator to move, and it is a standard of judging the performance of the oscillator. The performance can be improved by optimizing the geometry of the oscillator, which has to enable fluid jet to switch at low inlet velocity. For this, in this study the relationship between the pressure coefficient (difference) and geometric parameters is obtained through the analysis using the software FLUENT. From the results the optimized model that maximize the output pressure difference is obtained by using a cyclic coordinate method that is one of optimization methods. As a result not only the performance is improved, but also the working range is more widen.