Research on greenhouse and plant factory has been actively conducting to provide a stable growth environment. In plant factory, EC concentration (EC) and acidity (pH) of nutrient have a significant impact on physiological and morphological of plant. Therefore, EC and pH are important element for automatic control of nutrient solution. In this study, performance pH and EC sensors was evaluated for the responsiveness, accuracy and displacement. This study includes development of environmental monitoring system using pH and EC sensors which connected with computer and the pH and EC data was displayed in computer screen. PH buffer solutions were used in the experiments of seven kinds such as 4, 5, 6, 7, 8, 9, 10 res. EC of each standard solution in distilled water (0 μS / cm) were used in the experiments of seven kinds such as 100, 1000, 2070, 2764, 3900, 5000 μs / cm respectively. The experimental environment was kept in 25¡É and 50% humidity to control error. For evaluating the performance, measurement program was designed by control and instrumentation program (Labview 2010, National instrument Inc., Texas, USA) and data processing program carry out on data operation, storage, and display. Data was saved every 10 seconds. To evaluate the performance of the sensor, 1second interval and 10second intervals were used for 5minutes and 60minutes respectively for measuring accuracy. Also, for investigating whether nutrient or performance changes, cleaning sensors were compared to non-cleaning sensors. The error ranges were showed that pH was less than 2% and EC was 0 and 0.1 dS/m. From this study, these sensors are confirmed the appropriate sensors to measure the pH and EC of nutrient solution. For proposing sensor calibration and cleaning time, compared two statuses during 14 days in difference frequency for sensors correction and cleaning. One sensor was always in the nutrient and another one was corrected and cleaned in every 24 hours. Result showed the error of pH sensor was more than 5% after 6 days. Correction and cleaning of sensors are required within 6 days.