We propose new types of hybrid plasmonic waveguides for low-threshold nanolaser applications. Modal properties and lasing threshold under different geometric shapes and parameters are investigated and -analyzed by the finite element method, aiming to realize both low propagation and high field confinement. Results show that a smaller gap width and a larger round corner radius of the metal film reduce the lasing threshold. These new structures can open up new avenues in the fields of active plasmonic circuits.