The invention relates to a compound formation preparation method of a small-size rhenium and iridium engine combustion chamber. The compound formation preparation method of the small-size rhenium andiridium engine combustion chamber is mainly applied to small-size rhenium and iridium engine combustion chambers with high performance, wherein according to the small size, the diameter of a throat portion of one combustion chamber is no larger than 5 millimeters. According to the compound formation preparation method of the small-size rhenium and iridium engine combustion chamber, an inside-out preparation technology included accords with the dimensional characteristics of the small-size rhenium and iridium engine combustion chamber, and an iridium coating prepared with an arc ion plating technology is high in purity, good in thickness uniformity and high in preparation efficiency; and a rhenium coating prepared with a chemical vapor deposition technology is good in compactness, excellentin mechanical property, low in invalid deposit rate and less in follow-up machining amount. The compound formation preparation method of the small-size rhenium and iridium engine combustion chamber is good in adaptability and high in repeatability, and the prepared small-size rhenium and iridium engine combustion chamber is stable in performance and reliable in quality.