Heavy metal pollution in marine environments has become a prominent environmental problem. Many domestic and overseas scholars have conducted a great deal of research on the heavy metal pollution characteristics and accumulation specificity in crustaceans. Economically important crustaceans in aquaculture such as the Whiteleg shrimp (Penaeus vannamei), Summer flounder (Paralichthys dentatus), yellow croaker (Larimichthys crocea), Chesapeake blue crab (Callinectes sapidus), and Japanese blue crab (Portunus trituberculatus) are very popular foods but also have a high arsenic-enrichment factor. One of the most economically important marine aquaculture crabs in China, P. trituberculatus, has recently increased in popularity due to its high nutritional value and desirable flavor. The bioaccumulation of arsenic in the Gazami crab (Portunus trituberculatushas) has not been reported. Exploring the accumulation specificity of arsenic in P. trituberculatus provides the scientific data necessary to determine safe thresholds and arsenic limit in marine aquaculture. In our study, bioaccumulation of arsenic was studied in P. trituberculatus and simulated using the two-compartment model. The exposure concentration gradients of arsenic were 5, 20, and 100 μg/L. We analyzed data with non-linear curve fitting, obtaining the kinetic parameters such as bioconcentration factor (BCF), uptake rate constant (k1), elimination rate constant (k2), and biological half-life (B1/2). The results showed that the BCF of arsenic in the hepatopancreas was significantly higher than muscle. At the end of the enrichment experiment, the BCFs of arsenic in the hepatopancreas tissues of P. trituberculatus from low to high concentration groups were 21.21, 15.07, and 10.31, respectively. The uptake rate constant k1 and the BCF decreased with the increase of the aquatic arsenic concentration. The BCFs of arsenic in the muscle from low to high concentration groups were 5.17, 3.74, and 5.83, respectively. The kinetic parameters of the 5 μg/L and 100 μg/L experimental groups were similar. However, the uptake rate constant k1 was the smallest. The elimination rate constant k2 was the largest in the 20 μg/L experimental group, while the BCF and B1/2 were the smallest.