In the practical application of current environmental monitoring systems for the preservation of cultural relics, there are various problems, such as complicated wiring, poor network communication stability, high installation and maintenance costs and frequent battery replacement, etc. This work made a comparative study of the application status and characteristics of several mature network communication technologies used in environmental monitoring systems for the preservation of cultural relics. The existing 433 MHz technology monitoring system of Sichuan Museum was taken as an example to comparatively analyze the advantages and disadvantages of using three types of network communication technologies (433 MHz, LoRa and NB-IoT) through experiments of application scenes in the museum, from the perspectives of signal strength, packet loss rate and battery power consumption. We found that the 433 MHz technology-based monitoring system had obvious disadvantages, including complicated site wiring, high construction costs, difficult installation and maintenance, etc. By comparison, the LoRa or NB-IoT technology-based monitoring system could greatly reduce installation and maintenance costs, while also decreasing the transmission loss of intermediate nodes. However, the signal quality of all test points did not reach the coverage effect required for monitoring. This problem needed be solved by adjusting the deployment of monitoring systems and optimizing the network application performance. Based on these considerations,as well as practical requirements for the preventive conservation of cultural relics, we propose a new environmental monitoring system, which is convenient and quick in layout installation and low-cost in use and maintenance. This research provides a considerable reference for the network structure selection of environmental monitoring systems for the preservation of cultural relics, and for the construction of preventive conservation projects in museums.