A digital control primary-side regulation (PSR) flyback adapter with peak current delay compensation technique is proposed. In USB type adapters, over-current protection (OCP) or constant current (CC) control is used to protect the system. However, there is a primary-side peak current detection error caused by the propagation delay in control circuits, which makes the OCP and CC control incorrect. This paper proposes a digital method named as two-cycle-averaged compensation to solve current variation caused by the propagation delay. This work can reduce the cost of digital hardware, and without losing the compensation effect. The output current accuracy measurement result of this work is smaller than 2.8%.