To better guide the design of electrowetting liquid lenses, we propose a method for controlling their initial focal length. This method involves adjusting the microstructure of the electrode surface through low-power laser processing to change the contact angle of liquid lenses, thereby controlling the initial focal length. Using Wenzel theory, we derived the relationship between the initial focal length and geometric parameters (width and spacing) of the microstructural bumps. To validate this method, we conducted comparative experiments on three typical microstructures: cruciform, square, and concentric circular rings. Results show that the measured initial focal lengths of the concentric annular microstructures are consistent with the theoretical predictions. Additionally, these lenses have symmetrical shapes and smooth surfaces with no bumps. The centered radial microstructures are particularly effective for obtaining liquid lenses with good imaging qualities.