The invention belongs to the technical field of agricultural irrigation and particularly relates to a water-saving irrigation pipeline and a construction method thereof. The water-saving irrigation pipeline comprises a spodosol packing layer which is arranged in a foundation trench and a composite flexible pipe which is fixedly arranged in the spodosol packing layer, wherein the composite flexible pipe comprises a flexible pipe base layer, a PVC (Polyvinyl Chloride) coated layer and a PE (Poly Ethylene) thin-film layer from outside to inside. The construction method comprises the steps of material selection, foundation trench excavation, spodosol slotting, pipe laying, pipeline inspection, water-immersion compacting and the like. According to the water-saving irrigation pipeline, the problems such as pipeline breakage, water exclusion and operation difficulty which are brought by the structure and construction problems in the prior art are solved; the water-saving irrigation pipeline has the advantages of water-saving property, energy-saving property, land-saving property, simplicity and practicability in construction, short construction period and the like, and can be popularized in a large area, so that a new way is provided for saving water for the agriculture in China.