Revision of Indonesia seismic hazard maps would cause several changes in construction planning. In Pamekasan regency, there was an increasing in seismic load from maps of 2010 (kh=0,18) to 2017 (kh=0,22). So, it was necessary to be evaluated. Slope conditions with large loads and steep slopes can cause landslides so that slope reinforcement is needed. One of them is by using geotextile. This study aims to calculate the safety factor of slope (internal and external) with the influence of ratio between geotextile length and slope height (L/H) and vertical spasing of geotextile (Sv) which was done by using two calculations, namely manual calculation and Rocscience Slide 6.0 program. The results of the analysis show the decreasing of safety factor (SF) for unreinforced slope due to changes in the 2010 to 2017 seismic load of 5.263% calculated using Slide 6.0. Internal stability of pullout and rupture shows the decreasing of SF about 15,789%. External stability against sliding shows the decreasing of SF about 17,4% to 20,5%. External stability against overturning shows the decreasing of SF about 12,3% to 14,00%. External stability against bearing capacity failure shows the decreasing of SF about 35,2% to 36,6%. Global stability shows the decreasing of SF abou5,6% sampai dengan 6,4%.