A comprehensive review on the forming mechanisms of typical tight-sandstone hydrocarbon reservoirs was presen- ted. Based on pattern matching between oil migration period and tight reservoir evolution, typical tight sandstone reservoirs were summarized into three catgories: conventional tight sandstone reservoir, deep basin tight sandstone reservoir and com- posite tight sandstone reservoir. Through theoretical calculation, tight-sandstone hydrocarbon resources in China were reap- praised. The results reveal far more potential hydrocarbon resources than estimated before. The conventional hydrocarbon re- sources discovered so far account for less than 25% of the total basin hydrocarbon resources, while more than 75% of hydro- carbon resources concentrate in tight sandstone reservoirs with low porosity (〈12%) and low permeability (〈10^-3μm2). In the latter, over 25% of hydrocarbon concentrates in the tight conventional reservoirs, and over 50% in the tight deep-basin reservoirs. It is therefore suggested that tight hydrocarbon reservoirs remain the main focus in the future hydrocarbon explora- tions and sustainable developments.