The invention discloses a city tunnel monitoring data storage method and a city tunnel monitoring data storage system based on an XML (Extensive Makeup Language). The city tunnel monitoring data storage method comprises the steps as follows: firstly, carrying out data information acquisition on analog quantity information and switching value information of a city tunnel field environment; secondly, classifying the acquired data information to obtain analog quantity data and switching value data, periodically storing the analog quantity data in one XML document and storing the switching value data in another XML document in a triggered way; and lastly, transmitting the two XML documents to a superior monitoring system in real time. According to the invention, low redundancy, high definition and tractability in storage of data information of the tunnel monitoring system are guaranteed, and an analytical basis is provided for long-term tunnel monitoring data mining, tunnel decision support, data dump and data sharing.