The invention belongs to the field of signal processing and communication, and relates to a low complexity robust subspace estimation method. The method of the invention reduces the computation complexity, and mainly includes the steps of decomposing an unknown variable into a series of block variables, selecting block update rules, and then finding out an appropriate upper bound function corresponding to an original objective function to solve the target. The method of the invention is based on an uncertain block coordinate gradient descent, and avoids the computation overhead of a highly complex one-dimensional line search optimization problem by finding out a reliable approximate solution for each sub problem only through four arithmetic operations of vectors. Meanwhile, by introducing a new parameter adjustable robust function, the method avoids the computational problem brought by the non-smoothness of a cost function, and can also improve the robustness to abnormal points or impulsive noise.