The investigation of crimes against the sexual integrity of children requires the use of special psychological knowledge, which is due to the specifics of the most illegal actions and characteristics of children. Background is in the absence of developed protocols for investigating cases of sexual abuse of children. The given information of the article is based exclusively on the results of practical experience of the psychological expertise’s. The article describes the author's approach to the study of children - victims of sexual violence and presents the results of research protocol for assessing the signs of psycho-trauma of a child due to sexual violence.