The present invention provides a method of time-synchronized data transmission in induction type power supply system, comprising timers and programs installed in a supplying-end module and a receiving-end module to predict the time for generating the trigger signal at the receiving-end end and perform steps for detecting signals to avoid omission. Under the condition of high power transmission, power output on the supplying-end coil is pre-reduced prior to the time expected for receiving trigger data, making the main carrier wave amplitude decrease in a short time period. In every process of data transmission, timers are mutually calibrated and synchronized again to transmit power without detecting and receiving in the period when no data are expected to be transmitted, thus preventing interference of power load noise and enabling the induction type power supply system to transmit data code stably.