The molecular regulation mechanism of color polymorphism in animals is not determinate. Shell color variations often exist in many mollusca species. Rapana venosa, a well-known and economic species mainly distributed in Asian region, has three distinct color patterns, pure orange, pure dark stripes and part stripes. Here we combined the microsatellite, DNA methylation and transcriptome to assess the genetic diversity and molecular plasticity of three color patters of R. venosa. The external phenotypic traits among the three color patterns were not significantly different. The results from microsatellite markers indicated that the different color patterns of R. venosa had no significant genetic differentiation and each color group was relatively independent in gene flow. The DNA methylation demonstrated that each color pattern showed high methylation rate with more than 60%. The full-methylation rate for three color patterns were 34.47%, 35.67% and 32.54% respectively. The Gene Ontology (GO) classification and functional enrichment revealed three ontologies of molecular function, cellular components and biological processes. The function of translation, ribosomal structure and biogenesis accounted for the top classification, followed by general function prediction. We also revealed some functional genes, like Scavenger receptor cysteine-rich protein (SRCR), beta-carotene ketolase, tyrosinase proteins, Lustrin A, which were related with color and shell formation. Our study suggests that the color polymorphism of R. venosa is mostly attributed to the external environmental affection.