The jack mackerel () is one of the main catches in the northern South China Sea, and its spatial distribution is non-uniform. According to the two cycles of bottom trawl survey data in the northern South China Sea from 2014 to 2017 (2014-2015 is the first cycle, 2016-2017 is the second cycle), resource density is characterized by the catch per unit effort (CPUE). The Kolmogorov-Smirnov test (K-S test) was used to explore 11 probability distribution features. The results showed that the continental shelf area of the northern South China Sea had no obvious probability distribution, while the jack mackerel resource density in the Beibu Gulf obeys the lognormal distribution pattern, and the second cycle is more significant than the first cycle. At the same time, using a lognormal theory model (lognormal model and delta model) and an investigative design method (arithmetic method) to compare the estimation of the resource density within a certain area, we found that the lognormal model is more fit to describe the distribution characteristics of the density structure of jack mackerel, and the delta model is more suitable to estimate the jack mackerel resource density.