At the amendment of current Chinese civilprocedural law, the legislation has ruled the time limited of submitting evidence, butthe system of losing effect of defence has not been established till now.

A thorough understanding of defense invalidity in civil action is not only essential to reasonably establish litigation invalidity, but also essential to set up relevant law system.

By analyzing the legal theoretical foundation of the civil replies system and many malpractices initiated by the imperfection of the system,under the guidance of the fairness of the civil procedure and the benefit goal,the author induces several main points to construct relative perfect civil replies system.