The microlens with variable focal length is a novel microoptical component, which has wide potential application in the optical fields. A novel approach for tunable bifocal microlens has been proposed in this work, which is based on tunable refractive index resulting from Kerr effect in blue-phase liquid crystal. The finite element method has been used to simulate the controllable performance of tunable bifocal microlens, including the distribution of electric field, refractive index and optical field along propagation direction. The numerical calculation results show that the focused position of bifocal microlens can be effectively regulated by the changing of external applied voltage, which exhibits good optical performance. The presented microlens has many advantages, such as simple structure, easy to fabricate, easy to integrate with other photonic components, fast tuning speed and independence of optical polarization, which has a good potential application prospect in micro-optical system.