The realization of trial substantiation is the core of advancing the reform of trial-centered lawsuit system, Effective cross-examination of expert opinion in criminal cases will contribute to the implementation of it. Due to the lack of relevant cross-examination rules in legislation, the system of expert witnesses appearing in court and the system of expert assistants are not perfect. So that the defendant’s right of cross-examination is not fully implemented, and it will cause the cross-examination of the expert opinion to become a mere formality. In the future judicial practice, further improving the cross-examination system of expert opinions is intrinsically consistent with the requirements of the substantive trial. To promote the effective cross-examination of expert opinions, it is necessary to improve the relevant systems in a targeted manner to ensure that the appraisers testify in court, clarify the legal positioning of expert assistants, improve the cross examination system, and achieve effective cross-examination of expert opinions.