Objective: Prepare immunoaffinity column(IAC) for pre-processing Neurotoxic Shellfish Poisoning(NSP) samples, and to establish a method of IAC purification LC-MS/MS spectrometry for the NSP. Method:The IAC for the NSP was prepared by purification of PbTX-2 monoclonal antibody and agarose gel (Sepharose 4B) as carrier. The samples were extracted with 80% methanol aqueous solution, diluted with PBS buffer, purified and enriched by the IAC, and analyzed by LC-MS/MS. Meanwhile, the parameters of IAC such as sample solution and eluent were optimized. The results showed: The IAC for the NSP had a good purification effect on shellfish samples, reduced the interference of fat, protein, pigment, mucus and other impurities in shellfish matrix, and improved the recovery. In the range of 40~800 ng, the average recovery of standard addition was 82.95%~112.95%, and the relative standard deviation was 1.27%~2.94%. Conclusion: The IAC for the NSP can meet the needs of daily monitoring, with small matrix interference, strong purification effect and high sensitivity. It’s suitable for the analysis and determination of the NSP.