[Objective] To explore the changes in the particle size of pure milk during its storage period in order to monitor the changes in the taste and quality of pure milk.[Method]After pre-treatment of pure milk samples,a particle size detector was used to measure pure milk, and pure milk samples at different time intervals were selected for comparative study.[Result] The short-term shelf life storage time shows no significant change in the particle size of pure milk,and overall it remains in a relatively stable state.The long-term shelf life storage time showed a significant increase in the particle size value of pure milk over time. [Conclusion] By studying the changes in particle size of short-term and long-term shelf life pure milk samples,it was found that the changes in particle size values have a significant impact on the stability of pure milk during its shelf life,providing reference for the formulation of shelf life and monitoring of stability for other related products.