<p>The twisted and coiled polymer (TCP) artificial muscles driven by hydraulic pressure offer high mechanical efficiency and power density. The relation between geometry, mechanics, and actuation performance for this kind of muscle is crucial. In this study, we study the mechanics and actuation characteristics of TCP tube-based muscles driven by hydraulic pressure through experiment, theory, and finite element simulation. Accounting for the helical geometry and transverse isotropy of the TCP muscles, we develop a phenomenological model to predict the actuation performance of TCP tube-based muscles. The torsional and tensile actuation characteristics of the twisted and TCP tube-based muscle driven by hydraulic pressure are characterized. It is found that the cold drawing enhances the anisotropy of the polyvinyl chloride tube, resulting in an improved actuation performance of the twisted and TCP muscles. The torsional actuation in the twisted tube reaches the maximum at a critical bias angle for a given pressure, while the tensile actuation in TCP muscles increases with the coil diameter. The theoretical predictions and simulations are in good agreement with experimental results. This study is significant for guiding the design of TCP tube-based muscles and achieving their precise actuation control.</p>