The invention relates to a 2-chlorine-6,8-dihydro-5H-imidazo[2,1-c][1,4]oxazine. The compound can be used for providing a new choice for preparing 8H-imidazo[2,1-c][1,4]oxazine-2-carboxaldehyde,5,6-dihydro-(9CI). The compound is simple in structure, easy to prepare, and high in selectivity, cannot generate site 3 formyl isomer when preparing the 8H-imidazo[2,1-c][1,4]oxazine-2-carboxaldehyde,5,6-dihydro-(9CI), and is easy to separate and purify and high in product purity, so the cost of the whole process route for preparing the 8H-imidazo[2,1-c][1,4]oxazine-2-carboxaldehyde,5,6-dihydro-(9CI) from the compound is greatly reduced.