Corona viruses hijack human enzymes to assembly sugar coat on Spike glycoproteins. The mechanism that human antibodies may uncover the antigenic viral peptide epitopes hidden by sugar coat are unknown. In this study, we analyzed the high-resolution Cryo-EM structure of Spike glycoproteins. The results showed that electron densities of glycans cover most of the SARS-CoV Spike receptor binding domain except FSPDGKPCTPPALNCYWPLNDYGFYTTTGIGYQ. The glycosylated 2019-nCoV Spike protein by homology structure modeling showed a similar exposed sequence YQAGSTPCNGVEGFNCYFPLQSYGFQPTNGVGYQ. Other surface-exposed domains included those located on Central Helix, between amino acids 967 and 1016 of SARS-CoV, and 985 to 1034 of 2019-nCoV Spike protein. As the majority of antibody paratopes bind to peptide portion with or without sugar modification, we propose a snake-catcher model that a minimal length of peptide is first clamped by a paratope, and the binding is either strengthened by sugars close to peptide, or not interfered by sugar modification.