Paralytic shellfish poisoning (PSP) toxins could be neuromuscular paralysis agents, which could blocke the voltage-gated sodium channels, and then could cause holdback in nervous system transmission. Some bivalves could be tolerant of PSP toxins. The resistance mechanisms might be related to metabolism, biotransformation and the mutation of voltage-gated sodium channels, etc., in which the mutation of sodium channels might be the most important molecular mechanism of the resistance mechanism of bivalves.