This paper focuses on how to perform zero-voltage-switching (ZVS) control in GaN-based interleaved critical conduction mode (CRM) totem-pole power factor correction (PFC) rectifier with adaptive ZVS control. An improved variable-step adaptive control method is proposed to minimize control errors. Compared to methods with zero-current detection (ZCD), the adaptive ZVS method does not need current sampling. The status of ZVS can be measured by reverse conduction voltage comparison, and the synchronous rectifier (SR) on-time is tuned in control cycles. The control system is implemented in a microcontroller, and a 1.5 kW GaN-based interleaved PFC prototype is built with a peak efficiency of 98.9%.