Flexible optical channel data unit (ODUflex) is a new technique in the optical transport network (OTN) used to replace virtual concatenation (VCAT). For packet clients, it will be advantageous while ODUflex has the capability of hitless resizing like link capacity adjustment scheme (LCAS). A novel scheme is proposed in the paper for this purpose. The proposed scheme designs the new overhead (OH) and new protocol to achieve ODUflex hitless resizing. Moreover, it can be easily implemented in practical application.