Abstract: Sub-mesoscale process is characterized by Rossby number close to 1， 1km spatial scale magnitude and 1 day time scale magnitude. Based on high resolution Jason-2 satellite altimeter data and improved variance normalization and one dimension power spectrum analysis method，statistical analysis on Luzon Strait sub-mesoscale process with seasonal fluctuation characteristics is performed. The results show that the Luzon Strait sea level anomaly （SLA） fluctuation is strong in autumn and winter and it is relatively weak in summer. Identification results based on the power spectrum curve of the along-tract data shows that the corresponding seasonal fluctuation characteristics tallies with the SLA seasonal fluctuation. Finally， it is concluded that， combined with current research and case observations， high incidence of sub-mesoscale process in Luzon Strait may be the result of winter Kuroshio intrusions and the “volatility high-energy zone” on the both sides of Luzon Strait．