DescriptionTranscription involves many reaction steps and intermediates. Many phenomena in transcription kinetics are covered by ensemble average. Single-molecule DNA nanomanipulation techniques uncover these transcription kinetic events via determination of a transcription bubble in real time. In this dissertation, we focus on the transcription kinetics of bacterial RNAP. The study of transcription kinetics in this thesis can be divided into 4 main subjects: 1) The study of abortive initiation mechanism: Through a single-molecule DNA nanomanipulation technique, we tested the three models proposed for the mechanism of abortive initiation - inchworming, scrunching and transient excursion - on T5 N25 promoter. Of the three models, only the scrunching model involves a change in the size of the transcription bubble during abortive initiation, which was observed by single-molecule DNA nanomanipulation technique. 2) The study of the kinetics of elongation and termination: By introducing varying transcribed region lengths into DNA templates, the kinetics of elongation and terminator rewinding were studied. The resulting kinetics, determined by the single-molecule nanomanipulation technique, was analyzed by different regression methods. In the normal regression, the elongation velocity is 10 b/s and terminator rewinding takes 3.4 s on a tR2 terminator. Contrarily, through Poisson regression, the elongation velocity ranges from 6.4 b/s to 12.5 b/s and terminator rewinding takes 11.9 s on a tR2 terminator. 3) The study of a promoter sequence's effect: The effect from sequence of the T5 N25 promoter and T5 N25 antiDSR promoter in transcription was evaluated. The transcription bubble sizes of open complex and initial transcribing complex using the T5 N25 antiDSR promoters are larger than the ones from the T5 N25 promoter. The difference in the two promoter sequences does not have an effect on the transcription bubble size of an elongation complex. And elongation and terminator rewinding kinetics are not affected. On the other hand, abortive initiation and promoter escape are affected by the difference in the promoter sequence. 4) The study of the effect of transcription factor-GreB: The effect of transcription factor-GreB on abortive initiation was evaluated by the single-molecule DNA nanomanipulation technique. GreB does not affect the transcription bubble size during abortive initiation, but does reduce the lifetime of initial transcribing complex.