A rotary oscillator is a liquid-liquid extraction device used in chemical laboratories. Currently, domestic laboratories commonly employ oscillating extraction or manual dripping extraction methods for liquid-liquid chemical extraction. Both methods are rather cumbersome, inefficient, labor-intensive, and the organic solvents used during extraction can also pose health risks to laboratory personnel. The rotary oscillator operates fully automatically and consists of three main parts: the extraction bottle, a tunable frequency motor, and a time control system. The principle of the rotary oscillator involves a tunable frequency motor that causes the extraction agent to roll from top to bottom and then from bottom to top within the extraction bottle. When the extraction process is complete within the sealed extraction bottle, the extracted liquid and water sample are thoroughly mixed and collide vigorously, fundamentally solving the volatility issue of the reagents, ensuring more stable and reliable extraction results with genuinely credible data. This novel design is widely applicable for extracting substances such as oils, volatile phenols, anions, etc., from surface water, tap water, industrial wastewater, and domestic sewage.