In order to explore the application of carbon dots (CDs) in biosensors, this paper successfully prepared blue fluorescent carbon dots with excellent water solubility and stable optical properties by one-step hydrothermal synthesis using Meyerozyma guilliermondii PG-1 as raw material, and characterized CDs by transmission electron microscopy, Fourier infrared spectroscopy, X-ray electron diffraction and fluorescence spectroscopy. The obtained CDs were approximately round, with a size of about 11 nm, a large number of hydrophilic functional groups on the surface, and the strongest emission spectrum at 432 nm. CDs was further applied to the determination of trace tetracycline hydrochloride (TC) in water. The results showed that TC can rapidly quench the fluorescence of carbon dots based on static quenching and internal filtering effect, and the fluorescence quenching efficiency has a good linear relationship in the concentration range of 0.02-0.18 g·L^-1, indicating its potential application as a fluorescent probe for TC detection.