In the traditional system of dike monitoring, the acquisition apparatus is usually adopted with lots of built-in multiple data acquisition units. Each sensor is connected to the acquisition unit by wire, leading to the intensive use of wires. As a result, it is easy to cause inter-wire interference and signal distortion, compromising the accuracy and efficiency of dike monitoring. We have described and demonstrated a novel mode of signal acquisition that involved the integrated use of digital communication and human-computer interaction, and developed a separable online system of dike monitoring. Specifically, a parallel mode was adopted between the acquisition apparatus and the acquisition units; a serial mode was adopted between the acquisition unit and sensors; and a human-computer interface was used to control the monitoring process. Our research findings have shown that the parallel-serial mode not only proves to have a higher level of precision and efficiency than the serial mode, but also a simpler structure than the parallel mode alone under the same conditions. The acquisition unit adopting the parallel-serial mode could be separated from the acquisition apparatus and set up at nearby monitoring sites. This mode helps avoid such problems as massive amount of wiring as well as severe attenuation and interference of sensor signals in the serial mode, and is thus suitable for the linear dike monitoring. The parallel-serial mode has been successfully applied to the dike monitoring of the Yangtze River, and can also be used for scattered, linear, regional, and wide-range monitoring of engineering projects.