Abstract: With the continuous development of DNA extraction and testing technology, the DNA left at a crime scene plays a decisive role in the determination of criminal suspects in criminal investigation. But in the meanwhile, the anti-reconnaissance awareness of suspect is growing, which leads to a decrease of evidence left at scene during and after a crime. Therefore, in the process of evidence collection at scene, the finding and extraction of touch biological evidence, and the DNA detection are more and more important. At present, the proportion of touch evidence at the crime scene increases, which plays an increasingly important role in the detection of cases. However, with the characteristics of minute quantities, small size and secrecy, these touch evidence is difficult to be observed. What’s more, various forms of pollution at the scene greatly accelerate the degradation rate of trace material, thus, the test and analysis of such material has become the emphasis and difficulty of the forensic evidence identification. This article reviews different kinds, collection and extraction methods of touch DNA, the factors that affect the detection and the problems may meet in the detection for providing an application prospect to the forensic practice.

Key words: forensic genetics, DNA, review, touch DNA