Horizontal well SRV (Stimulation Reservoir Volume) is the core technology to develop tight oil and gas reservoirs at home and abroad. At present, the main technologies include multi-stage fracturing technology with pumping bridge plug, multi-stage fracturing technology with hydraulic jet and fracturing technology with open hole packer, but they cannot satisfy the technical require- ments on low cost and efficient SRV of horizontal wells due to the limitation of displacement rate, drilling plug and full bore. And this limitation will be more and more serious with the increase of horizontal section length. In this paper, therefore, the horizontal-well staged fracturing technology with casing ball seat was proposed. Its technical principle is as follows. Firstly, preset the working barrel on the casing for well cementing and completion, pump the dedicated perforation-releasing combination tool to the preset location during the fracturing, release the elastic ball seat to the preset working barrel on the casing and connect it. Secondly, lift up the combination tool and carry out multi-cluster perforation. Finally, release the soluble ball to the elastic ball seat to isolate the lower layer and carry out multi-cluster staged fracturing with bare casing. The key tools were developed, including the preset working barrel, the elastic ball seat and the soluble ball, and the construction technological parameters were optimized and tested on site. Thus, the SRV technical targets were realized, including integrated multi-cluster perforation combination of long horizontal section, high-rate fracturing, drilling free and fast commissioning after fracturing and large bore. It was tested in 6 wells and the success ratio is 100%. Among these 6 wells, the longest horizontal section is 1 525 m long. The effect of efficiency increase and cost reduction is remarkable with production test period shortening by more than 30%, operation cost reducing by more than 10% and single-well production rate increasing by more than 20%. It is promising in popularization and application.