Objective To provide theoretical reference for the research on lateral postural control in older people by using the electromyography （EMG）technique to compare the neuromuscular reaction between the young and older people during lateral perturbation. Methods Postural reactions of 14 young people and 14 older people as subjects were evoked by sudden unpredictable medio lateral translation platform. The surface EMG data were collected from peroneus longus, anterior tibialis, gluteus medius and erector spinae of the left side of the body. Results The latencies in anterior tibialis, gluteus medius and erector spinae were obviously delayed in older people, and the duration of time to peak in peroneus longus, anterior tibialis and gluteus medius of older people was much longer than that of young people. Conclusions The delayed response of ankle, hip and trunk muscle and the low efficacy of contraction rate in ankle and hip muscles to the unexpected perturbation might be the primary reason for the decrease of lateral postural control in older people.