Abstract: Based on data of underway survey with Nansha sea area collected by acoustic method in four seasons of 2013, we analyzed fishing grounds of Sthenoteuthis oualaniens in Nansha sea area. Acoustic detection of biomass was used as indicator of fishing grounds after normal transformation. The results showed that there was very strong spatial correlation of S. oualaniens fishing grounds in four seasons, and the nugget effect values of variation function were all less than 0.25. Using the variable function, different theoretical models were fitted respectively by different seasons. Exponential model was the best fitting model in summer and autumn, while spherical model in spring and Gaussian model in winter. The models fitted better for summer and winter than for the other two seasons, which also had stronger spatial correlation. The results of Kriging spatial interpolation analysis of different seasons showed that the higher biomass of fishing grounds was most centralized in the region near the island, which had obvious characteristics of patchy distribution. The fishing grounds of S. oualaniens had a tendency to move south gradually over time. According to the result of cross validation of theoretical value and observed value, the theoretical models and Kriging interpolation of different seasons are appropriate.