Abstract: In this paper， a facilitated CFAR detector is developed for MIMO array radar， where a distinctive feature of MIMO array radar， large observation space， is used to suppress clutter and jammer by way of directly filter out clutter and jammer subspace. The facilitation of this CFAR detector lies in the fact that the clutter subspace can be estimated off-line and stored in the memory， and the jammer subspace can be estimated in lowdimension space， by reason that it is not samples in other rangecells but the known system parameters， the clutter subspace structure and the block-diagonal property of jammer covariance matrix that are used to estimate the clutter and jammer subspaces. Based on the ideal model of clutter， simulations show a high accuracy of clutter subspace estimation can be obtained with appropriate estimation method， and also show the detection performance of the resulted CFAR detector approaches that of the detector with known clutter and jammer subspaces.