Embodiments of the present disclosure provide a method and a system for determining a blood flow parameter of a reticular vessel. The method may be implemented on a device including at least one processing device and at least one storage device. The method may include: obtaining vessel data of an object; generating a reticular vessel model by performing, based on the vessel data, vessel segmentation; generating, by performing model partitioning based on the reticular vessel model, a plurality of vessel sub-models; and determine the blood flow parameter of the reticular vessel model by performing, based on the plurality of vessel sub-models, coupling processing.