The present invention discloses a novel modified live attenuated Fowl Adenovirus (FAdV) CRISPR-based vaccine. This invention alters the genotype sequence of FAdV into a less virulence, genetically stable, immunogenic and feasible vaccine to be applied in countries with FAdV outbreaks. This invention applies the use of CRISPR technology to produce attenuated virus rather than the conventional continuous passaging method which is time-consuming, costly and prone to technical errors. This vaccine is easy and cost-effective to produce, as well as suitable for administration on an industrial basis.