Abstract: Empirical research shows that there are difficulties in the application of written testimony of witnesses who do not appear in court in cross examination, examination and certification. The concrete performance is that the rate of acceptance is low, the reason of court authentication is one-sided and fuzzy, the rule of evidence review is applied wrongly, and there are different opinions on whether they have the qualification of evidence . The reason is that the written testimony provided by the witness who did not appear in court has natural credibility defects, the private subject's self written testimony lacks obvious recognizable signs, the academic circles have differences on this kind of evidence's admissibility, the direct verbal principle is overemphasized, and the value of the written principle is improperly devalued. In the transitional period when the system of witness appearing in court tends to be perfect and the litigation environment changes qualitatively, it is necessary to standardize the rules of production, cross examination, examination and determination of written testimony, and enhance the credibility and admissibility of written testimony, so as to activate its due evidential value and alleviate the contradiction between high utilization rate and low acceptance rate of written testimony.