Being minimally invasive and highly effective, radiofrequency ablation (RFA) is widely used for small size malignant tumors treatment. However, in clinical practice, a large number of tumors are found in irregular shape, while the current RFA devices are hard to control their morphologic appearance of RFA lesions on demand, which usually ends up with unnecessarily excessive tissue ablation and subsequently often brings irreversible damage to the organs’ functions. Here, we introduce active cannulas for each of individually-controlled sub-electrodes to achieve an on-demand shape morphing and thus conformal RFA lesion. The target shape as well as the length of inserted sub-electrodes can be precisely controlled by tuning the active stylets and cannulas. What’s more, owing to independent movement and energy control of each sub-electrodes, our electrode is shown to be not only efficient enough to accomplish accurate trajectory control to target tissue in a single insertion, but also adaptive enough to ablate target tissues with diverse morphologic appearances and locations. On-demand conformal ablation of target tissue is demonstrated as well under the guidance of ultrasound imaging with our device. Potentially, our RFA electrode is a promising minimally invasive treatments of malignant tumors in the future clinical practice. Corresponding author(s) Email:    [email protected]