Abstract: A set of tight sedimentary tuff reservoirs were found in Tiaohu formation of the Middle Permian in Santanghu basin, which formed a tight hydrocarbon accumulation play integrated with source and reservoir rocks. This paper presents the formation mechanism of the tight sedimentary tuff reservoir from sedimentary structural setting and source?reservoir formation feature, and analyzes the controlling factors of such a reservoir of Tiaohu formation in Mazhong area in Malang sag. The reservoir shows that distributions of the Tiaohu sedimentary tuff reservoir and high?quality source rocks are controlled by paleo?lake basin formed during the volcanic eruptions intermittent period;the compact superimposition of the organic matter?rich shale and the underlying high porosity?extra low permeability sedimentary tuff provide good conditions for petroleum charging into the tight reservoir; the wide flat slope in the paleo?lake basin and its hinterland are the favorable positions for high?quality source rocks and good reservoir development; the Niujuanhu south slope, Mazhong area and Shibandun area in Malang sag and Tiaohu sag are the favorable domain for Tiaohu tight reservoirs exploration in Santanghu basin