In multiple-input multiple-output(MIMO) interference channel, multiple transmitters and receivers communicate simultaneously as a pair. We establish the metric for node pair selection algorithm to maximize the sum rate in MIMO interference channel. In this paper, by adjusting node pairs properly, we show that the sum rate can be enhanced. We propose two different node pair selection algorithms to improve the sum rate of MIMO interference channel. Firstly, we propose an optimum node pair selection algorithm by formulating a node pair selection metric to select the best node pairs among all possible node pairs. Then we propose a sub-optimum node pair selection algorithm to lower computational complexity. We confirm from some numerical simulations that the proposed algorithms offer significant sum rate enhancement compared to the case when node pair selection is not considered.