The uncertainties of environmental parameters affect the robustness of detection method in complex shallow water. We define and estimate the angle-domain subspaces of horizontal linear array in a proper way under an uncertain environment. According to the angle-domain subspaces, we propose an angle-domain subspace detector and its robust form. Angle-domain subspaces contain an uncertain information by using the observation matrices in different environmental parameters. The relationship between the horizontal wave number of propagating modes and the sound speed of the bottom and sediment in hard seabed is used to estimate the angle-domain subspaces. The proposed angle-domain subspace detector is robust in an uncertain environment, but its detection performance fluctuates with target bearings. The angle domain subspace is transformed into a constant dimension subspace, robust form of the angular domain subspace detector, whose detection performance is consistent in all source bearings. The simulation results in the uncertain shallow-water environment show that the robust angle domain subspace detector has a similar robustness to the energy detector, and better detection capability.