This paper proposes a digital multi-mode flyback adapter with primary-side regulation(PSR). To enable multi-mode operation, including continuous conduction mode (CCM) and discontinuous mode (DCM), in the PSR flyback, a digital control scheme with simple compensation method is proposed to modulate the output voltage. In practical applications, PSR flyback converters are often used as adapters. In this work, the digital controller is implemented with FPGA and includes constant voltage (CV) control, constant current (CC) control, and quasi-resonant valley switching to enhance efficiency, meeting application requirements. In terms of system performance, the voltage and current regulation of the system under input voltages ranging from 90 to 264Vac achieve results of ±3.5% and ±6.8%, respectively.