Abstract: According to the physical requirements and the actual situation of Positron Emission Tomography (PET) cyclotrons at Institute of Modern Physics, Chinese Academy of Sciences (IMP, CAS), a new compact RF cavity with a quarter wave resonator structure and a profiled cover was designed with high accelerated e-field gradient. Additionally, a special dual tuning structure with a short-plate and a movable capacitor plate was designed to meet the requirements of complicated tuning operation mode. The simulated results from Microwave Studio (CST) showed that the design obtained a high quality factor and reached a rated accelerated voltage. The electro-magnetic analysis was carried out, and the power loss tolerance and the thermal distribution were calculated. A prototype cavity was fabricated and measured in January, 2013, and the tested results indicated that the accelerated voltage was higher than 50 kV and the frequency stability was 10-6/d, both of them reached the original design specification. This proves that the measured results agree well with the simulated ones. All detailed simulations and measurements were analyzed and discussed.