Abstract: In the age of network information, communication methods are constantly upgraded. The General Provisions of Civil Law responds to this trend, Article 137 paragraph 2 sentence 2 determines whether the declaration of intent in the form of a data message is effective when there is no convention and the criterion for determining is "access to the relevant system". However, this rule does not fully apply to fax, e-mail, instant messaging tools, etc, and this rule is a little gruff. When interpreting this provision, we should re-use the traditional theory of effectiveness of a declaration of intent. First, the information carrier makes the declaration of intent physical, which is the standard for distinguishing between "conversation mode" and "non-conversation mode", declaration of intent without carrier and with carrier correspond to "non-conversation mode" and "non-conversation mode" respectively. Second, we should consider the reasonable allocation of trading risks. In special circumstances, we must adjust the theory of "reachingism" and "understanding". Third, we must take into account the factual elements and normative elements of "arrival" of the declaration of intent in the form of a data message and rule out situations that should not be considered arrivals under the "normal circumstances".