Monitoring macronutrients in hydroponic nutrient solution is a vital task for tomato growth. Ionselective electrodes (ISEs) were used to detect the NO3N, K+, Ca2+ concentrations. The slope and bias correction (SBC) method was applied to alleviate the signal drift of ISEs due to continuous immersion in nutrient solutions. The slopes of response Nernst equation for NO-3, K+, Ca2+ ISEs were decreased to 0.05, 0.39 and 0.04, and intercept potentials were reduced to 0.12mV, 0.93mV and 0.10mV, respectively. It indicted the capacity of slope and bias correction method as improving the repeatability and consistency of each ISE’s Nernst equation. Then the NO3N, K+ and Ca2+ concentrations were predicted by Nernst model, and they were measured by spectrographic method to provide standard values. The predicted accuracy of NO3N, K+, Ca2+ concentrations was improved after using slope and bias correction method, providing by the relative errors were significantly reduced from 43.31%, 38.46% and 93.83% to 5.99%, 7.44% and 27.96%，respectively. It was obvious that the results obtained from ISEs coupled with slope and bias correction method could indeed reflect the macronutrients component in tomato nutrient solutions. The assimilation of macronutrients was activated in flower stage, with the decrease of 45.19%, 36.46% and 27.92% for NO3N, K+ and Ca2+ concentrations, respectively.