In order to improve the assessment effect of college students' physical health status, this paper combines big data technology to evaluate college students' physical health status with the support of intelligent physical health monitoring system. This paper starts with the introduction of the current mainstream physical health data frequency synthesis technology, analyzes the principle and structure of DDS and PLL, and expounds their respective advantages, disadvantages and application scenarios. Moreover, this paper analyzes some technical indicators when DDS and PLL devices are used in the fabrication of frequency synthesizers for physical health data, including phase noise, spurious suppression, and frequency switching speed. Through the experimental analysis, it can be seen that the assessment system of college students' physical health status based on big data analysis constructed in this paper can play an important role in the assessment of college students' physical health status.