Abstract: In strong winds, impact of windborne debris on building envelope is a main reason that be responsible for chain-like and regional disasters. Accurately understanding the trajectory of windborne debris is crucial for disaster prevention and mitigation. This paper focuses on the common six degree-of-freedom (6-DOF) windborne debris and introduces a theoretical model of the three-dimensional (3D) trajectory. The improved Euler and 4th-order Runge-Kutta methods are respectively presented for solving the trajectory model. Using the data from the Wind Tunnel Laboratory at the University of Auckland, two numerical algorithms are compared and the influence of different factors on trajectory simulation is analyzed. It is found that using the 4th-order Runge-Kutta method can simulate the trajectory of windborne debris more accurately and efficiently. The influence of the flight potential and aerodynamic configuration of the windborne debris on trajectory simulation is revealed, based on which the time step suggestion function is proposed.