Abstract: We present and demonstrate a fiber-optic sensor based on single-ended detection that measures both temperature and refractive index. The cladding of the two microsphere-structured fibers is spliced together, and the end of the fiber is coated with an aluminum film to increase reflection, thereby forming a microsphere structure sensing head. The experimental results show that the temperature sensitivity and refractive index of the device can reach 50.77 pm/℃ and -21.94 nm/RIU, respectively. This work presents a low-cost, high-resolution and simple fiber-based approach to versatile sensing applications.