Disclosed is a power control system of adaptive control of turn on time, including a primary side digital controller, a secondary side synchronization controller, a rectification unit, a power unit, a transformer unit, a primary side switch unit, a current sensing unit, a secondary side switch unit, and a secondary side output capacitor for implementing a function of flyback power conversion. The secondary side synchronization controller is intended to turn on or off the secondary side switch unit to achieve a synchronization function of rectification, and the primary side digital controller reduces a primary side drain-source voltage of the primary side switch unit and a secondary side drain-source voltage of the secondary side switch unit by reducing a current sensing limit used to compare with the current sensing signal. The power control system thus greatly improves stability and endurance of the overall operation.