Precision control of the concentration of fertilizer is an important part of the integrated control system of water and fertilizer. It is the foundation to realize precision fertilization by detecting the electric conductivity (EC) value of fertilizer and controlling it in a reasonable range. Based on Internet of things technology, the remote control system was designed and developed, self-tuning fuzzy PID control algorithm was introduced into the equipment in the terminal, and the fuzzy PID control algorithm was used to control the local end frequency of variable frequency pump, and in turn to realize the precise control of EC value, and the local end PID and remote end fuzzy PID control algorithm were validated through the contrast test. The results showed that the larger the target EC value was, the more accurate the steady-state EC value was, but the steady-state time and overshoot were increased. Compared with the traditional local PID control, the response speed of the system was fast, the EC fluctuation range was small and stable. When the target EC value was 2.5mS/cm, the steady-state time and overshoot reached the maximum, which were 120s and 20.8%, respectively. The mixing time and measured EC value could meet the actual demand of water and fertilizer control. The research not only realized the remote fuzzy PID control of EC value, but also realized the irrigation data monitoring and switching control of the computer, mobile phone and WeChat multi-terminal of the irrigation and fertilization system.