To understand the formaldehyde content of common seafood and its products from different provinces in China.Methods 530 samples from 6 kinds of common seafood and its products (ice fresh squid, water-swollen squid, shredded squid, shrimp, shelled shrimp and grilled fillet) were collected randomly from rural markets and city supermarkets in 8 provinces, and the samples were analyzed by the determination of formaldehyde content in food-high performance liquid chromatography (HPLC) method. Results The formaldehyde was detected in all 6 kinds of seafood and their products. The detection rate was 40.57%, and the range of content was 0.00-950.00 mg/kg. The average content of formaldehyde in descending order were shredded squid, water-swollen squid, grilled fillet, ice fresh squid, shelled shrimp and shrimp, and the detection rate were 52.78%, 57.45%, 42.50%, 57.45%, 23.08% and 12.24%, respectively.Conclusion Formaldehyde contents were different in different kinds of seafood and their products, that may rooted in the formaldehyde baseline, its changing rule or illegal adulteration. Overall, it should be concerned if the formaldehyde content was above 100 mg/kg, especially above 200 mg/kg.