The thermoacoustic cooler is one of promising technique for utilization of unused thermal energy. The object of this paper is to study the improvement of performance in a single-loop type thermoacoustic cooler by designing of the new structure consisted of looped tube, bypass-looped tube, and two stacks as the double-loop type thermoacoustic cooler. Using finite difference time-domain (FDTD), pressure, particle velocity and phase difference were numerically simulated. Experiments were also performed to measure the cooling performance of the thermoacoustic cooler under constant electric power supplying to a speaker. Firstly, it was found that, by connecting the bypass-looped tube, the sound field was changed. As the results, the resonance frequency decreased, and the profile of velocity amplitude was shifted in the looped tube. Secondary, thermoacoustic cooling was realized in both of stacks in each looped tube due to thermoacoustic heat pumping effect. The total cooling performance of the proposed the double-loop type thermoacoustic cooler was improved in comparison with the single-loop type thermoacoustic cooler.