Blood is a prevalent carrier of biological information at crime scenes, often present in various forms and intermixed with environmental substances. Deciphering the age of bloodstains can offer crucial clues and investigative directions for revealing the truth behind crimes and discovering evidence. Spectral analysis technology, renowned for its rapid and non-destructive testing capabilities, has emerged as a classic technique in the analysis of bloodstains. This paper delineates the biochemical conversion processes and influential factors associated with bloodstains, with a particular emphasis on advancements in modern spectral analysis technology for studying bloodstain aging patterns. The aim is to offer concrete references and insights for the application of these techniques in forensic science research.