Abstract: Dried tangerine peel is one of the most important ingredients in many Chinese dishes, due to its excellent medicinal properties. However, the current aging of the dried tangerine peel has been confined to the prolonged processing time, low efficiency, and uneven aging on the peel surface. Taking the Xinhui tangerine peel as the object, this study aims to develop a mist spraying device for the aging treatment. The microbial droplets of solution were sprayed onto the surface of the tangerine peel for better aging. The key components were then selected to optimize the structural parameters for the mist spraying. A twin-fluid atomization nozzle with a fan shape was selected to test the parameters, according to the particle size analyzer of the droplets. A control system was also developed for the device. The sauter mean diameter (D32) of the droplets was also determined at the various nozzle-to-surface distances. The results show that the small D32 values were represented by the uniformly fine diameters of the droplets. There was no statistically significant difference in the D32 within the nozzle-to-surface distance range of 32-38 cm, indicating the uniform distribution of the droplets. The hollow gap of the spray conveyor was set at 40 cm, which was smaller than the 55 cm radius of the storage basket. As such, the basket of the tangerine peel was prevented from falling off when passing through the gap. The control cabinet primarily consisted of three components: an industrial personal computer (IPC), a programmable logic controller (PLC), and a frequency converter (FC). In the PLC, an STM32F103 microprocessor was used to control the FC. The three-phase asynchronous motor was then regulated to drive the operation of each conveyor. The atomization spraying was also adjusted to control the solenoid valve for the constant output pressure of the air compressor via the closed-loop PID control. The RS-485 communication protocol was adopted for the data transmission and control instructions between the IPC and PLC. The graphical user IPC interface was designed using Python and the QT framework. A series of experiments was conducted on the atomization spraying to identify the optimal parameters of the equipment during operation. The coverage of the droplet was determined to evenly cover the core area of the storage basket. After that, the uniform coverage was achieved under either 0.8 MPa spray pressure with 40 or 50 Hz FC frequency, or 0.85 MPa spray pressure with 60 Hz FC frequency. Subsequently, the droplet deposition tests were performed to identify the optimal parameters at the moisture content (i.e., an increase of no more than 2 percentage points). The moisture content increased by 1.67 percentage points under 0.8 MPa spray pressure and 50 Hz FC frequency, and by1.60 percentage points under 0.85 MPa spray pressure and 60 Hz FC frequency. Both optimizations fully met the various conditions in the field. Finally, the relatively uniform size of the droplets was observed on the tangerine peel surface under 0.8 MPa spray pressure and 50 Hz FC frequency. The mist spraying was achieved in the uniform coverage of the droplets, fully meeting the requirement of the moisture content. The consistent distribution of the droplet size was also maintained for better spraying performance. The mist spraying equipment can be expected to drive the mechanization and standardization of the aging process. The finding can also provide a useful reference for the tangerine peel aging in fields.