This paper proposes research schemes for a tricopter based on its developing trend. It focuses on its mechanical structures and physical moments and solves the problem that moments in the system offset each other. Then , it analyzes aircraft attitudes on launching, pitching, rolling and yawing by aerodynamic analysis and establishes a mathematical model for the tricopter. Finally, the PID and Linear Quadratic Gaussian(LQG) control methods are used to design a controller for the tricopter. The results show that the PID method does not achieve the desired states for its long equilibrium time and overmuch oscillations. However, after improving the controller by the LQG method, the simulation experiments on step functions and pulse response functions from different channels show that the response speed of the control has increased, and the balance of control can be implemented by about 2 s. the research can provide theoretical function for controlling aircraft attitudes.