A non-contact blood pressure measurement method was proposed and achieved based on theoretical deduction of the relationship among pulse transit time, heart rate and blood pressure. Pulse transit time was estimated using heart rate and phase difference of pulse wave which were obtained from color videos through imaging photoplethysmographic. Parameters of the functional relationship were determined through curve fitting with experiment data. Error analysis was processed with an Omron electronic sphygmomanometer as reference to verify the accuracy of blood pressure obtained using the proposed method. The error of acquired systolic blood pressure varied from -2.40 to 3.43 percent. The error of acquired diastolic blood pressure varied from -6.88 to 5.26 percent. © 2018 SPIE.