Abstract: A biarc trajectory and its guidance law are proposed to satisfy the constraints of impact angle, impact time and missile dynamics in missiletarget engagement. Under the constraints of the initial and terminal flight path angles, the analytical solution and the feasible solution set of biarc trajectories are deduced by using the tangent relationship between two arcs. Based on the relationship between biarc trajectory and its tangent point, the biarc trajectories which satisfy the dynamics constraint, impact time constraint or energy optimality are generated. Then the biarc guidance law, which does not need rangetogo information, is designed based on the circular geometry and missiletarget geometry. Simulation results demonstrate the proposed guidance law can satisfy complex guidance constraints, and it can provide comparable results to the optimal guidance law in terms of energy optimality.