The technology of underwater rock plug blasting includes chamber blasting, drilling blasting and the combination of both. The advantages and shortcomings of these three approaches and the application conditions are analyzed as follows: chamber blasting releases great power and thus is suitable for thick rock plug with large cross section ； whereas drilling blasting, with evenly distributed power, can be applied in the blasting of small and medium  sized rock plug ； and the combination of the both can be applied more widely in different engineering circumstances. The structural characteristics of double rock plugs in parallel sections are analyzed, based on which a blasting plan combining the large diameter deep hole and shallow hole blasting is proposed. Techniques of the blasting are also summarized for reference for alike projects. The water intake project of Tangzhai Power Plant is taken as an illustration.