Rumen pH value and temperature are key indicators of rumen fitness. It is difficult to implement traditional measurement, and the traditional rumen pH value measurement trends to cause cross infection. A wireless measurement unit for rumen pH value and temperature was designed. A star Sub-1G wireless network was also designed to monitor multiple cows. An Alibaba Cloud interface was developed to display rumen pH value and temperature. The wireless measurement unit used LabSen331 pH electrode to measure pH value and employed Pt1000 to sense temperature. AD8603 operational amplifier and AD7792 analog to digital converter were used to amplify and convert signal. STM8L151 microcontroller was employed to process data. The data was transmitted to collar node with 315MHz wireless signals. Wireless transmission network was built based on TI-15.4 protocol. When data was acquired by a collar node, it was further sent to the collector. The collector sent data to gateway through UART. The gateway transmitted data to Alibaba Cloud through 4G network according to MQTT protocol. pH value and temperature measurement accuracy, power consumption of measurement unit, and reliability of wireless transmission network were examined. The error of the pH value measurement was less than ±0.02. The temperature measurement error was less than ±0.3℃. The measurement unit used a 2200mA·h/3.6V lithium battery for power supply. When the measurement interval was set to be 10min, the battery was able to work more than 1800 days. The range of reliable wireless signal transmission was about 180m. Test in dairy farming showed a significant correlation between the recorded values of the monitoring system and the manually measured pH value of the rumen liquid (r=0 .961, P<0.05).The monitoring system was able to monitor the changes of rumen pH value and temperature continuously, which provided reference for the fitness monitoring and the strategy of precision feeding.