In a new optical hybrid switching environment which combined Optical Burst Switching (OBS) and Optical Circuit Switching (OCS), we propose flow-level service classification scheme for IP differentiate service. In particular, this classification scheme classifies incoming IP traffic flows into short-lived and long-lived flows for Quality of Service (QoS) provisioning according to traffic characteristics such as flow bandwidth, loss and delay. In incoming IP service classes, long-lived flows include premium service and loss sensitive service to take an advantage of OCS. On the other hand, short-lived flows include Best-Effort service and delay sensitive service to take an advantage of OBS. Therefore, optical hybrid switching network can take advantages of both switching technologies using the proposed flow classification scheme. The aim of proposed technique is to maximize network utilization while satisfying user's QoS requirements. We show results for the delay, OBS burst size and burst assembly times.