Glucose is not only as a main metabolic material, but also as a signaling molecule during the process of plant growth. In this work, for the first time, we developed an electrochemical microbiosensor suitable for real-time detecting of glucose concentration in plants. The biosensor uses glucose oxidase (GOD) to catalyze the glucose, and uses cellulose acetate (CA) and polycarbonate (PC) to improve the electrochemical selectivity and reduce the dependence of response on ambient oxygen. The linear range of the proposed sensor is wide and the detection limit is lower, which could basically meet the needs of plant testing. The content of glucose in sunflower under salt stress was monitored in real-time successfully, confirming the applicability of the fabricated microbiosensor. This work has a potential to open an innovative way to study the dynamic changes of physiological state of the plants in real-time.