This paper tries to make a new explanation from the specific angle of reliability regulation of the evidential marker “cong X lai shuo”. The core function of the evidential marker is to provide indispensable support for the insufficient confidence assertion Y. According to the semantic character of X, “cong X lai shuo” can be divided into definite perspective type and fuzzy perspective type. For Y with sufficient reliability, “cong X lai shuo” assumes the function of enhancing reliability by the following means: (1) making the proposition omnidirectional; (2) focusing the statement object; (3) making the presentation content precise; (4) making the judgment criterion clear. For Y with insufficient reliability, “cong X lai shuo” assumes the function of improving reliability by the following means: (1) blurred perspective; (2) degree adjustment; (3) perspective change; (4) specific conditions.