Generally, in the tropical countries and particularly in Benin one of the main risks that threatens the life of the human, animal and plant beings is the drought. The objective of this research is to analyze the vulnerabilities to the drought of the study area, in order to evaluate their influences on the pastoral ecosystems of the center and north of Benin. For this to happen, the Pluviometrics Indications of Deficit and the pluviometrics discrepancy have been determined. The mapping results permitted to evaluate and to extract the area occupied by each modality of vulnerability. The analysis of the results shows the zones with low vulnerability to the drought are more extended (2 554 316,78 Ha) with a cover area of 65,50% of the study area and an unequal distribution. While the zones with moderate vulnerability to the drought are of about 1 022 637,48 ha and occupy 26,22% of the study area. Whereas the zones with strong vulnerability to the drought (322 729,738) occupy 8,28% of the study area.