Gyroplane is becoming popular these days for its characters of security,reliable and simple operation.Modeling is the first step that put mathematical theory into engineering studies such as aircraft stability,control and handling qualities.Considering the variable rotoring speed,propeller,tail aero forces and moment,this paper explores the mathematical model of an unmanned mode gyroplane based on integrating rotational equations of motion.Then we investigate in this work the simulation model at steady-state condition for some given independent variables.Variation of angle of attack,pitch angle and rotoring speed with the shaft angle,collective pitch angle and throttle for a given steady forward velocity are presented and discussed in detail.For the specific layout,propeller thrust vector above the center of gravity,large control quantities are likely lead to PIO,which is verified by trim results and control response simulation.