The invention relates to a transformer station secondary screen cabinet temperature and humidity monitoring system based on Raspberry Pis and Java language, a computer serves as a client, an instruction is input and a result is displayed, Raspberry Pis serve as servers and control temperature and humidity measurement modules connected thereto to measure, and the system is controlled by programming in JAVA language. The client and the Raspberry Pi servers are connected through a local area network, communication therebetween is performed through a TCP/IP protocol, network interface programs are compiled in the client and Raspberry Pi system respectively, and data exchange and transmission are realized through Java programs of two sides. Programs for function realization of the monitoring system include four main program modules: a control temperature and humidity measuring module, a Raspberry Pi server communication module, a client communication module and a client visual interface module. The transformer station secondary screen cabinet temperature and humidity monitoring system can enable a power grid operation maintenance department to rapidly and accurately know the temperature and humidity condition in the secondary screen cabinet in real time, timely discover the environment temperature and humidity standard-exceeding condition, and to take effective measures to dispose, thereby ensuring that secondary equipment runs at appropriate temperature and humidity.