Provided are a catalyst for dehydration reaction of a primary alcohol, a method for preparing the same, and a method for preparing alpha-olefins using the same. According to the present invention, there is provided a catalyst for dehydration reaction of primary alcohols capable of adjusting the strength and distribution of Lewis acid sites (LASs) on a surface of an alumina catalyst to realize high selectivity to alpha-olefins as well as a high conversion rate in the dehydration reaction of primary alcohols. Therefore, high-purity alpha-olefins having a low isomeric yield fraction as well as a high conversion rate can be produced from the primary alcohols.