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 1.5kW GaN-based interleaved PFC prototype is built with a peak efficiency of 98.9%.