Abstract: A maximum a posteriori probability (MAP) algorithm was proposed for the multiple-input multiple-output with orthogonal frequency division multiplexing (MIMO-OFDM) systems, which reduces the computation complexity via the expectation maximum (EM) algorithm to decompose the MIMO channel estimation into a series of independent single-input/single-output(SISO) channel estimation. Besides, according to that the MIMO channels between sending and receiving antennae in an angle domain approximate to spatial independence, the most significant taps (MST) technique was employed to reduce the effect of noise on estimated performance. Simulation results indicated that the proposed algorithm gets lower estimation error at low SNR than conventional LS and EM algorithms.