We propose a loop-reduction LLL (LR-LLL) algorithm for lattice-reduction-aided (LRA) multi-input multioutput (MIMO) detection. The LLL algorithm is an iterative algorithm that contains many check and process operations; however, the traditional LLL algorithm itself possesses a lot of redundant check operations. To solve this problem, we propose a look-ahead check technique that not only reduces the complexity of the LLL algorithm but also produces the lattice-reduced matrix which obeys the original LLL criterion. Simulation results show that the proposed LR-LLL algorithm reduces the average number of loops or computation complexity. Besides, it also shortens the latency <i >of clock cycles</i> about 19.4%, 29.1%, and 46.1% for <svg style="vertical-align:-0.3135pt;width:32.700001px;" id="M1" height="11.075" version="1.1" viewBox="0 0 32.700001 11.075" width="32.700001" xmlns="http://www.w3.org/2000/svg"> <g transform="matrix(1.25,0,0,-1.25,0,11.075)"> <g transform="translate(72,-63.14)"> <text transform="matrix(1,0,0,-1,-71.95,63.5)"> <tspan style="font-size: 12.50px; " x="0" y="0">4</tspan> <tspan style="font-size: 12.50px; " x="9.0271664" y="0">×</tspan> <tspan style="font-size: 12.50px; " x="19.804752" y="0">4</tspan> </text> </g> </g> </svg>, <svg style="vertical-align:-0.3135pt;width:32.700001px;" id="M2" height="11.075" version="1.1" viewBox="0 0 32.700001 11.075" width="32.700001" xmlns="http://www.w3.org/2000/svg"> <g transform="matrix(1.25,0,0,-1.25,0,11.075)"> <g transform="translate(72,-63.14)"> <text transform="matrix(1,0,0,-1,-71.95,63.5)"> <tspan style="font-size: 12.50px; " x="0" y="0">8</tspan> <tspan style="font-size: 12.50px; " x="9.0271664" y="0">×</tspan> <tspan style="font-size: 12.50px; " x="19.804752" y="0">8</tspan> </text> </g> </g> </svg>, and <svg style="vertical-align:-0.3135pt;width:48.325001px;" id="M3" height="11.075" version="1.1" viewBox="0 0 48.325001 11.075" width="48.325001" xmlns="http://www.w3.org/2000/svg"> <g transform="matrix(1.25,0,0,-1.25,0,11.075)"> <g transform="translate(72,-63.14)"> <text transform="matrix(1,0,0,-1,-71.95,63.5)"> <tspan style="font-size: 12.50px; " x="0" y="0">1</tspan> <tspan style="font-size: 12.50px; " x="6.2515001" y="0">2</tspan> <tspan style="font-size: 12.50px; " x="15.278666" y="0">×</tspan> <tspan style="font-size: 12.50px; " x="26.056252" y="0">1</tspan> <tspan style="font-size: 12.50px; " x="32.307751" y="0">2</tspan> </text> </g> </g> </svg> MIMO systems, respectively.