The low inertia power system with a high proportion of asynchronous power sources has insufficient anti-interference ability. Before the primary frequency response, the frequency drop caused by disturbance may trigger low-frequency load shedding risk, and it is urgent to allocate sufficient fast frequency response resources. A fast frequency response reserve allocation method based on the coordinated optimization of DC frequency limiting controller （FLC） and energy storage is proposed to address issues such as the lack of a domestic fast frequency response reserve system, limited optimization space for FLC reserve, and insufficient utilization of energy storage multiple functions. Firstly, based on the operational characteristics of the DC interconnection line in the sending-end system, a fast frequency response economic allocation method for reserve capacity is proposed, which combines DC FLC with energy storage. Secondly, based on the multiple time scales regulation characteristics of energy storage, a energy storage utilization mode considering multifunctional regulation capacity stacking and reuse is proposed. On this basis, a regional spot market clearing model is constructed for the coordinated optimization of DC FLC and energy storage, achieving rapid frequency response and day-ahead full time optimization of the system's reserve. Finally, the effectiveness of the configuration method and clearing model proposed in this paper is verified through a simulation case of clearing the spot market in the southern region of China.