A horizontal movement simulator is designed in this study. The random motion displacements generated by broad band B spectrum and narrow band J spectrum are studied experimentally by using a horizontal movement simulator. Statistical characteristics such as the maximum/ minimum displacement and standard deviation of random motion displacement generated by ocean wave spectrum and determinate coefficient between corresponding measured power spectrum density and theoretical spectrum are analyzed by varying significant wave height and peak period. The determinate coefficient between measured power spectrum density and theoretical spectrum of B spectrum is greater than that of J spectrum, which is mainly affected by peak period for J spectrum. The standard deviation of the random motion displacement and the variance of power spectrum density of Jspectrum are also found to be greater than that of B spectrum. The result indicates that it is difficult to generate random motion displacement exactly by a horizontal movement simulator for more highly dispersed J spectrum compared with broad band Bretschneider spectrum.